Functionalized Phenanthrene Imide-Based Polymers for n-Type Organic Thin-Film Transistors

Area of Science:

• Organic electronics
• Polymer chemistry
• Materials science

Background:

• High-performing n-type polymers are essential for advancing organic electronics.
• Limited availability of electron-deficient building blocks with suitable properties hinders development.
• Imide-functionalized polycyclic aromatic hydrocarbons (PAHs) are promising candidates due to their electronic and structural characteristics.

Purpose of the Study:

• To report novel functionalized phenanthrene (PhA) derivatives as building blocks for n-type polymers.
• To investigate the impact of dual functionalization with electron-withdrawing groups on PhA properties.
• To evaluate the performance of derived polymers in organic thin-film transistors (OTFTs).

Main Methods:

• Synthesis of two functionalized PhA derivatives, CPOI (carbonyl-imide) and CPCNI (dicyanomethylene-imide).
• Incorporation of imide and carbonyl or dicyanomethylene groups onto the PhA framework.
• Development of two polymers, PCPOI-Tz and PCPCNI-Tz, using the synthesized building blocks.
• Fabrication and characterization of organic thin-film transistors (OTFTs) using the developed polymers.

Main Results:

• The dicyanomethylene-modified CPCNI exhibited a stabilized LUMO energy level (-3.84 eV) due to synergistic inductive effects.
• The polymer PCPCNI-Tz demonstrated improved electron mobility compared to PCPOI-Tz.
• PCPCNI-Tz showed a significantly decreased threshold voltage in OTFT applications.
• The dual functionalization strategy effectively enhanced the electron-deficient nature of the PhA building blocks.

Conclusions:

• Two novel, structurally unique electron-deficient building blocks, CPOI and CPCNI, were successfully synthesized from phenanthrene.
• The dual functionalization of PhA with strong electron-withdrawing groups is an effective strategy for designing high-performance n-type polymers.
• The developed n-type polymers show promise for applications in organic electronics, particularly in organic thin-film transistors.