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Delocalizing Excitation for Highly-Active Organic Photovoltaic Catalysts.

Authors :: Zhang Z
Xu C
Sun Q
Zhu Y
Yan W
Cai G
Li Y
Si W
Lu X
Xu W
Yang Y
Lin Y
Source :: Angewandte Chemie (International ed. in English) [Angew Chem Int Ed Engl] 2024 Jun 21; Vol. 63 (26), pp. e202402343. Date of Electronic Publication: 2024 May 23.
Publication Year :: 2024
Abstract: 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 <superscript>-1</superscript> g <superscript>-1</superscript> ) 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 <superscript>-2</superscript> ).<br /> (© 2024 Wiley-VCH GmbH.)