Delocalizing Excitation for Highly‐Active Organic Photovoltaic Catalysts

• Published in: Angewandte Chemie International Edition 2024-06, Vol.63 (26), p.e202402343-n/a
• Main Authors: Zhang, Zhenzhen, Xu, Chaoying, Sun, Qianlu, Zhu, Yufan, Yan, Wenlong, Cai, Guilong, Li, Yawen, Si, Wenqin, Lu, Xinhui, Xu, Weigao, Yang, Ye, Lin, Yuze
• Format: Article
• Language: English
• Subjects: Carrier lifetime; Catalysts; Catalytic activity; Charge efficiency; Crystallization; Current carriers; Delocalizing Excitation; Dielectric constant; Dielectric strength; Electron-Phonon Coupling; Energy of dissociation; Excitons; Heterojunctions; Hydrogen evolution; Nanoparticles; Organic Photovoltaic Catalyst; Photocatalysis; Photocatalysts; Photocatalytic Hydrogen Evolution; Photoexcitation; Photovoltaics
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.202402343

Localized excitation in traditional organic photocatalysts typically prevents the generation and extraction of photo‐induced free charge carriers, limiting their activity enhancement under illumination. Here, we enhance delocalized photoexcitation of small molecular photovoltaic catalysts by weakening their electron‐phonon coupling via rational fluoro‐substitution. The optimized 2FBP‐4F catalyst we develop here exhibits a minimized Huang–Rhys factor of 0.35 in solution, high dielectric constant and strong crystallization in the solid state. As a result, the energy barrier for exciton dissociation is decreased, and more importantly, polarons are unusually observed in 2FBP‐4F nanoparticles (NPs). With the increased hole transfer efficiency and prolonged charge carrier lifetime highly related to enhanced exciton delocalization, the PM6 : 2FBP‐4F heterojunction NPs at varied concentration exhibit much higher optimized photocatalytic activity (207.6–561.8 mmol h−1 g−1) for hydrogen evolution than the control PM6 : BP‐4F and PM6 : 2FBP‐6F NPs, as well as other reported photocatalysts under simulated solar light (AM 1.5G, 100 mW cm−2). The electron‐phonon coupling in organic photovoltaic materials (2FBP‐4F) was reduced through a rational fluoro‐substituted strategy, promoting exciton delocalization. Polaron pairs and polarons were observed in 2FBP‐4F nanoparticles, facilitating the generation of free charge. 2FBP‐4F exhibited high photocatalytic performance in both single‐component and heterojunction systems.