Hydrogen-Bonding Interactions Between Terpolymers Enable Excellent Device Efficiency and Operational Stability of Non-Halogenated Solvent-Processed Polymer Solar Cells

Although polymer solar cells (PSCs) have shown considerable power conversion efficiency (PCE) potential, their poor operational stability is a major obstacle for their future commercialization. In this study, the ternary-blend strategy based on D1-A-D1-D2-type conjugated random terpolymers containing hydrogen-bonding sites is employed to simultaneously improve device efficiency and long-term stability. Notably, the PM6-ThEG:PM6-ThOH:Y6-BO ternary-blend system exhibits a remarkable PCE of 17.2% with superior photo, thermal, and mechanical stability, outperforming those of binary devices based on PM6, PM6-ThEG, and PM6-ThOH polymer donors. These outstanding results are likely attributed to the robust molecular lock via hydrogen bonds between PM6-ThEG and PM6-ThOH terpolymers, which can induce strong intermolecular packing, a dense 3D terpolymer network, and optimized morphology. These results also correlate well with the computational study. A comprehensive analysis of optoelectronic and morphological properties as well as the exploration of underlying physical mechanisms collectively verifies the effectiveness of this approach based on mixed random terpolymers with hydrogen-bonding moiety to achieve the non-halogenated solvent-processed PSCs with exceptional efficiency and operational stability. Random-terpolymerized donors containing hydrogen-bonding sites are strategically designed and convergently synthesized for highly efficient and stable PSCs processed from halogen-free solvent. By this strategy, the PSC based on PM6-ThEG:PM6-ThOH:Y6-BO ternary system delivers a remarkable PCE of 17.2% with superior photo, thermal, and mechanical stability, which is ascribed to molecular lock via hydrogen-bonding interactions between photoactive materials. image