Conformation‐Locking in Thiazole‐Rich Mixed‐Linkage Covalent Organic Frameworks for Spontaneous Exciton Dissociation and Efficient Photocatalysis

ABSTRACT The formidable exciton effect inherent in organic semiconductors fundamentally restricts free charge carrier generation, thereby impeding photocatalytic redox efficiency. Facilitating spontaneous exciton dissociation and lowering exciton binding energy are essential for maximizing charge utilization. Herein, we report a conformation‐locking strategy to engineer a thiazole‐rich mixed‐linkage donor–acceptor conjugated covalent organic framework (SBt‐Tapt) via post‐synthetic cyclization. The seamless integration of sulfur heteroatoms into a rigid, thiazole‐bridged framework significantly enhances π‐conjugated and electronic polarizability. Crucially, this structural reinforcement lowers the exciton activation energy below to 25 meV, triggering spontaneous exciton dissociation, extending carrier lifetimes, and yielding a proliferation of free charge carriers at room temperature. Mechanistic insights elucidate that the thiazole moieties synergistically activate adjacent phenyl units for O 2 reduction while simultaneously lowering the energy barrier for H 2 O oxidation at benzothiophene sites. This dual‐pathway mechanism drives efficient H 2 O 2 photosynthesis with robust operational stability exceeding 100 h. Notably, utilizing phenolic pollutants as proton donors, SBt‐Tapt delivers an exceptional H 2 O 2 evolution rate of 8.99 mmol g cat −1 h −1 alongside effective pollutant mineralization. This study elucidates a profound structure–activity relationship (SAR) and establishes conformation locking as a potent excitonic engineering paradigm for developing high performance organic photocatalysts.