Polythiophene Block Copolymer–Perylene Diimide-Based Electron Donor–Acceptor Double-Cable Polymer and Its Potential as an All-Organic Photocatalyst for Artificial Photosynthesis of H₂O₂

Enhancing the light energy harvesting and conversion capabilities of all-organic photoactive materials is of significant scientific interest. Herein, we report the synthesis of a photoactive double-cable polymer (DCP) consisting of a polythiophene (PTh) block copolymer electron donor (D) conjugated to a perylene diimide (PDI) electron acceptor (A). GRIM polymerization and postsynthetic modifications are employed to synthesize the block copolymer [P3HT-b-poly(3-HT-co-PTh/PDI)] consisting of a poly-3-hexylthiophene (P3HT) block and a block comprising of randomly distributed repeat units bearing hexyl and PDI groups. Besides 1H NMR, ATR-FTIR, UV/visible, and fluorescence spectroscopic characterizations, AFM and XRD analyses are performed to reveal self-assembly and crystallinity behaviors. Compared to P3HT, PDI, and their physical hybrid (P3HT–PDI-PH), the P3HT-b-poly(3-HT-co-PTh/PDI) shows superior D–A electronic communication, higher (photo)electrochemical current, faster electrochemical kinetics, and lower charge transfer resistance. The photocatalytic performance of all photocatalysts in the artificial photosynthesis of H2O2 is demonstrated over 10 photocatalytic cycles. Comparing the results from the highest H2O2 producing cycles, the photocatalytic performance of P3HT-b-poly(3HT-co-Th/PDI) is ∼2.1, ∼3.2, and ∼1.9 times superior compared to that of P3HT, PDI, and P3HT–PDI-PH, respectively. In summary, this work contributes to the development of organic semiconducting polymer-based photoactive materials for application in light energy harvesting and conversion technologies.