Flow-directed molecular weight control of conjugated polymers

초록

The molecular weight of conjugated polymers is a key factor determining the performance of organic electronic and photonic devices. Thus, producing polymers with the optimal molecular weight in a reproducible manner is crucial. In conventional batch synthesis, however, targeting a specific molecular weight is challenging due to the random nature of step-growth polymerization and batch-to-batch variations, which hinder reproducibility. In contrast, continuous flow synthesis offers fine-tuning of reaction parameters and high reproducibility for systematic optimization through intrinsically enhanced heat and mass transfer and a high surface-to-volume ratio. In this study, we demonstrated flow-directed molecular weight control of PM7 D1, a high-performing conjugated polymer. By controlling the flow parameters, including reaction time, catalyst loading, solvent, and monomer concentration, in a customized flow system, PM7 D1 was achieved reproducibly with specific number-average molecular weights (Mn) of 30, 40, and 50 kDa. Organic photovoltaic devices fabricated from these polymers to reveal an optimal molecular weight, and a high power conversion efficiency of 8.01% was achieved with 40 kDa PM7 D1.

키워드