Photoinduced Accumulative Electron-Transfer Dynamics in Perylene Diimide Polymers as Photoredox Catalysts

Understanding the mechanisms of light-driven charge separation (CS), accumulative electron transfer, and free carrier (FC) dynamics in polymer semiconductors as photoredox catalysts is essential for artificial photosynthesis and for developing efficient solar energy conversion materials. This study presents a comparative investigation on the photoinduced electron transfer dynamics of three perylene diimide (PDI) polymers, o PDI, m PDI, and p PDI, that differ by their phenylenediamine linkers. Notably, o PDI, which is constructed with ortho-phenylenediamine linkers, exhibits the fastest two-electron CS and the subsequent FC generation among this series. These superior properties are attributed to its large molecular dipole moment and driving force for multielectron accumulation. The high photocatalytic activity of o PDI was further verified through two independent two-electron quenching experiments and the oxygen reduction reaction (ORR). The latter efficiently generates H₂O₂, particularly in the case of o PDI, leading to the rapid degradation of uric acid (UA). This work elucidates the mechanism of photoinduced accumulative electron transfer in PDI-based polymers and provides a theoretical framework for the rational design of efficient multielectron accumulation systems in advanced photocatalytic applications.