A Tricyclic Framework with Integrated B←N and Cyano Dual Functionalization for Superior n-Type Organic Electronics

Area of Science:

• Materials Science
• Organic Electronics
• Polymer Chemistry

Background:

• High-performance n-type organic electronics require conjugated polymers with low-lying lowest unoccupied molecular orbital (LUMO) energy levels.
• Synthesizing effective electron-accepting units with strong electron-withdrawing capabilities remains a significant challenge in materials design.

Purpose of the Study:

• To develop novel acceptor building blocks for n-type conjugated polymers by functionalizing anthracene with dual electron-withdrawing groups.
• To synthesize and characterize new copolymers incorporating these building blocks and evaluate their performance in organic thin-film transistors (OTFTs) and organic thermoelectrics (OTEs).

Main Methods:

• Peripheral functionalization of anthracene with dual N,O-bidentate BF2/B(CN)2 groups to create DBNF and DBNCN acceptor building blocks.
• Synthesis of copolymers (PDBNF and PDBNCN) using these novel monomers.
• Characterization of copolymer properties, including LUMO levels, molecular packing, and performance in OTFTs and OTEs.

Main Results:

• DBNF and DBNCN exhibit enhanced electron-withdrawing properties, extended π-backbones, and improved molecular packing compared to single-moiety counterparts.
• Synthesized copolymers PDBNF and PDBNCN show significantly suppressed LUMO levels (≈-4.0 eV).
• PDBNF achieves high electron mobility (3.04 cm²/V·s) in OTFTs, while PDBNCN demonstrates excellent conductivity (95.5 S/cm) and power factor (147.8 μW/m·K²) in n-doped OTEs.

Conclusions:

• The introduction of dual B←N and cyano functionalities is an effective strategy for designing high-performance n-type conjugated polymers.
• The developed materials show great promise for advancing solution-processed n-type plastic electronics, particularly in OTFTs and OTEs.