Terminal-Group Engineering to Amplify Asymmetric Electronic Interactions in COFs for Enhanced Optoelectronic Performance.

Covalent organic frameworks (COFs) have emerged as highly promising platforms for optoelectronic applications due to their tunable architecture, extended π-conjugation, and adjustable electronic properties. Introducing asymmetric electronic structures has proven effective in promoting charge separation and transport, thereby enhancing photoelectric conversion efficiency. However, existing strategies to amplify such asymmetry largely rely on the design of new monomers or modification of linkage types. In this work, we present a terminal-group engineering strategy to amplify the intrinsically weak asymmetric interactions in sp² carbon-conjugated COFs. This approach enables precise modulation of electronic structure and photophysical behavior, resulting in enhanced charge mobility and significantly improved photocatalytic performance. The engineered COFs demonstrate nearly a 4-fold increase in hydrogen peroxide production relative to their unmodified counterparts, while exhibiting excellent structural stability and long-term operational durability. These findings establish terminal-group engineering as a powerful and generalizable design strategy for developing high-performance COF-based optoelectronic and photocatalytic materials.