Non-covalent Intramolecular Interactions Induced High-Performance Terpolymer Donors

Abstract

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···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···O non-covalent intramolecular interactions to improve the planarity of polymer donors. © 2023 Wiley-VCH GmbH.