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.