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Cyano-Functionalized Pyrazine: A Structurally Simple and Easily Accessible Electron-Deficient Building Block for

Lijun Tu¹, Junwei Wang², Ziang Wu³

¹Key Laboratory of Functional Molecular Solids, Ministry of Education, School of Chemistry and Materials Science, Anhui Normal University, No.189, Jiuhua South Road, Wuhu, Anhui, 241002, China.

Angewandte Chemie (International Ed. in English)

|January 24, 2024

Summary

New cyano-functionalized pyrazine building blocks enable low-cost, high-performance n-type polymer semiconductors for organic thermoelectrics (OTEs) and organic thin-film transistors (OTFTs). These materials offer facile synthesis and deep LUMO energy levels, crucial for advancing organic electronics.

Keywords:

acceptor-acceptor polymers cyano-functionalized pyrazine electrical conductivities electron-deficient building block n-type organic thermoelectrics

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Area of Science:

Materials Science
Organic Electronics
Polymer Chemistry

Background:

Development of cost-effective, high-performance n-type polymer semiconductors is critical for advancing organic thermoelectrics (OTEs).
Designing electron-deficient building blocks with simple structures and facile synthesis is key to achieving this goal.

Purpose of the Study:

To synthesize novel cyano-functionalized pyrazine building blocks for n-type polymer semiconductors.
To develop acceptor-acceptor (A-A) polymers based on these building blocks for applications in organic thin-film transistors (OTFTs) and OTEs.

Main Methods:

Synthesis of 3,6-dibromopyrazine-2-carbonitrile (CNPz) and 3,6-Dibromopyrazine-2,5-dicarbonitrile (DCNPz) building blocks.
Polymerization of CNPz and DCNPz with DPP to form P(DPP-CNPz) and P(DPP-DCNPz) acceptor-acceptor polymers.
Characterization of polymer properties, including energy levels, electron mobility, and electrical conductivity after doping.

Main Results:

Successfully synthesized CNPz and DCNPz building blocks via cost-effective, multi-step reactions.
Developed A-A polymers P(DPP-CNPz) and P(DPP-DCNPz) with deep lowest unoccupied molecular orbital (LUMO) energy levels.
Achieved high unipolar electron mobilities of 0.85 cm²/Vs for P(DPP-CNPz) and 1.85 cm²/Vs for P(DPP-DCNPz).
Obtained high n-type electrical conductivities (25.3–33.9 S/cm) and power factors (30.4–41.4 μW/mK²) upon N-DMBI doping.

Conclusions:

Cyano-functionalized pyrazine building blocks (CNPz and DCNPz) are effective for creating high-performance n-type polymer semiconductors.
These materials offer a promising, low-cost alternative for advancing organic electronics, particularly in OTFTs and OTEs.
The facile synthesis and tunable electronic properties make these building blocks valuable for future materials design.