Noncovalent Macrocyclic Encapsulation via Terminal "Dynamic Locking" Enabling High-Performance Nonfused Ring Electron Acceptors.

Nonfused ring electron acceptors (NFREAs) have garnered significant attention recently; however, designing high-performance NFREAs remains challenging, where achieving an efficient charge transport channel via precisely controlling molecular packing and aggregation compactness is crucial. Herein, we proposed an innovative noncovalent macrocyclic encapsulation molecular strategy for high-performance NFREAs, and 3TT-Ph1 was designed and synthesized by introducing terminal phenyl lateral chains surrounding the trithieno[3,2-b]thiophene (3TT) core with an inward orientation. These terminal phenyl motifs induce intramolecular macrocyclic locking through C-H···π and π-π interactions, which create an undisturbed encapsulated environment for the conjugated core and guarantee efficient charge transport in the backbone. Notably, such a noncovalent "dynamic locking" also endows the molecule with good processability in solution and allows effective morphology regulation. Finally, the device based on D18:3TT-Ph1 achieved a champion PCE of 18.40%, with enhancements of 42% and 19% relative to the control molecules of n-butyl-functionalized 3TT-1 and cyclohexyl-terminated 3TT-Cy1, ranking among the highest efficiencies for organic solar cells (OSCs) based on NFREAs. Our research demonstrates that noncovalent macrocyclic encapsulation via aromatic functionalization at the alkyl terminal is a rational route to create an efficient charge transport channel for high-performance NFREA design.