Molecular bridge engineering in covalent organic frameworks for enhanced electronic transport

Area of Science:

• Materials Science
• Nanotechnology
• Organic Electronics

Background:

• Conductive 2D COFs have intrinsic π-conjugation but suffer from grain boundaries limiting charge transport.
• Effective charge transport in COF thin films is crucial for advanced electronic applications.

Purpose of the Study:

• To develop a scalable strategy for enhancing electrical conductivity in 2D COF thin-film devices.
• To overcome limitations imposed by grain boundaries and amorphous regions in COFs.

Main Methods:

• Bridging polycrystalline COF domains with molecularly dispersed conjugated polymers (CPs).
• Guiding COF-CP selection based on electronic alignment, geometric compatibility, and chain-length criteria.
• Assembling COF-CP heterostructures and evaluating their electrical properties.

Main Results:

• Identified specific COF-CP combinations exhibiting significantly enhanced conductivity.
• Demonstrated that optimal bridging occurs below the CP crystallization threshold, requiring short-range ordered or near-amorphous CPs.
• Achieved ppb-level NO2 sensing by combining COF porosity with CP-mediated charge transport.

Conclusions:

• A rational polymer-bridging strategy effectively enhances conductivity in COF-based electronic materials.
• This approach is compatible with wafer-scale fabrication and opens new avenues for high-performance sensors.
• Key design parameters for extending this strategy to other COF-CP systems were identified.