Acceptor Backbone Cationization via B ← N Functionalization Enables High-Performance Porous n-Type Organic Mixed...

Area of Science:

• Materials Science
• Organic Electronics
• Bioelectronics

Background:

• High-performance n-type organic mixed ionic-electronic conductors (OMIECs) are crucial for organic electrochemical transistors (OECTs) in bioelectronics.
• Current OMIECs often use hydrophobic polymers, limiting ionic transport.
• A need exists for OMIECs with enhanced hydrophilicity and ionic conductivity.

Purpose of the Study:

• To introduce a novel ionic acceptor design strategy for n-type OMIECs.
• To synthesize and characterize new cationic polymer OMIECs.
• To evaluate the performance of these OMIECs in OECTs and bioelectronic sensors.

Main Methods:

• Developed backbone cationization via B ← N functionalization in bipyridine and bipyrazine frameworks.
• Synthesized two n-type ionic polymer OMIECs: PBPyBF3 and PBPzBF3.
• Characterized material properties (LUMO levels, torsional barriers, microstructure, film morphology, capacitance) and OECT performance (transconductance, figure of merit).

Main Results:

• Synthesized cationic polymers with low LUMO levels (-4.0 eV), high torsional barriers, and ordered microstructures.
• Achieved enhanced hydrophilicity and porous film morphology due to cationization.
• Demonstrated significantly improved volumetric capacitance (581 F cm⁻³).
• OECTs based on PBPzBF3 showed record normalized transconductance (38.9 S cm⁻¹) and figure of merit (215.9 F cm⁻¹ V⁻¹ s⁻¹).
• Integrated PBPzBF3-OECTs in electrocardiogram sensors achieved high signal-to-noise ratios and sensitivity.

Conclusions:

• Backbone cationization via B ← N coordination is an effective strategy for designing hydrophilic n-type OMIECs.
• The developed OMIECs enable high-performance OECTs for advanced bioelectronic applications.
• Established fundamental structure-property relationships for ion-electron coupled transport in conjugated polymers.