Non-covalent Intramolecular Interactions Induced High-Performance Terpolymer Donors

Ternary polymerization are demonstrated as a feasible and successful method of optimizing absorption, energy level, and crystallinity by maintaining the excellent properties of a polymer matrix. However, the third unit inevitably interrupts the periodic sequence distribution of the ordering packing of conjugated backbones, and thus balancing the trade-off between the advantages of the third component and the disruption caused by the nonperiodic sequence distribution remains a great challenge. Herein, two terpolymer donors L1 and L2 are developed by introducing diethyl-5,5 '"-dibromo-4,4 '"-bis(2-ethylhexyl)-[2,2 ':5 ',2 ''-terthiophene]-3 ',4 '-dicarboxylate (DDT) unit as the third component. Owing to the electron-deficient ability and S center dot center dot center dot O non-covalent intramolecular interactions of DDT, terpolymers L1 and L2 displays deeper energy levels, enhanced molecular rigidity, and planarity than PM6. After blending with L8-BO, the L1-based polymer solar cells exhibit well miscibility with L8-BO, leading to a more well-defined nanofibrous morphology, face-on orientation, and a slight energy loss in the blend films. As a result, the optimized L1:L8-BO-based device achieves a record power conversion efficiency (PCE) as high as 18.75%. This work provides a feasible strategy to develop high-performance polymer donors via utilizing S center dot center dot center dot O non-covalent intramolecular interactions to improve the planarity of polymer donors. Two terpolymer donors L1 and L2 are developed by combined esterylthiophene-based DDT unit as the third component to polymer matrix PM6. Thanks to the S center dot center dot center dot O non-covalent intramolecular interactions of DDT unit, the L1:L8-BO-based device exhibit well-defined nanofibrous morphology and preference face-on orientation, yielding a record power conversion efficiency of up to 18.75%.image