Acidic Electron Acceptors in Imine-Linked Covalent Organic Framework for Enhanced Gas Sensing With Field-Effect...

Semiconducting covalent organic frameworks (COFs) that combine structural order with porous characteristics are promising candidates for chemiresistive sensors. Understanding carrier transport behavior and improving their electrical properties remain critical challenges due to the low intrinsic conductivity of semiconducting COFs and the difficulty of electronic device fabrication. Herein, we propose a strategy that introduces acidic electron acceptors into a semiconductive COF, Py-1P, to modulate its electrical properties. Comprehensive characterizations confirmed charge-transfer interactions between electron acceptors and imine bonds, achieving a chemical doping effect. The modified COF-based chemiresistors exhibited a significantly enhanced sensing response for detecting sub-ppm NO₂ gas, among the best reported chemiresistive sensors. The measurement of COF-based field-effect transistors (FETs) revealed a one-order-of-magnitude enhancement in mobility upon the p-type doping, indicating the corresponding relationship between carrier density and mobility in polycrystalline COFs. These findings provide a comprehensive understanding of doping effects and carrier transport in the semiconductive COF, establishing a foundation for optimizing COF-based electronic devices.