Towards single-crystalline two-dimensional poly(arylene vinylene) covalent organic frameworks.

Area of Science:

• Materials Science
• Polymer Chemistry
• Organic Electronics

Background:

• 2D conjugated polymers, specifically 2D poly(arylene vinylene)s (2D PAVs), show potential in optoelectronics, photocatalysis, and electrochemistry.
• Conventional synthesis methods often yield poorly crystalline or inaccessible 2D PAVs, limiting their performance.

Purpose of the Study:

• To develop a novel strategy for synthesizing highly crystalline 2D PAVs with precise crystallization control.
• To investigate the impact of crystallinity on the charge transport properties of 2D PAVs.

Main Methods:

• A Mannich-elimination strategy was employed to convert 2D imine-covalent organic frameworks into 2D PAVs via reversible C=C bond formation.
• Techniques including high-resolution transmission electron microscopy and continuous rotation electron diffraction were used for structural characterization.
• Charge transport properties were measured and compared between crystalline and amorphous 2D PAVs.

Main Results:

• The Mannich-elimination strategy successfully produced 11 highly crystalline 2D PAVs with diverse lattice structures (honeycomb, square, kagome).
• The synthesized 2D PAVs exhibited high specific surface areas (up to ~2,000 m² g⁻¹) and significant lattice-mismatch tolerance.
• Benzotrithiophene-based 2D PAVs demonstrated charge mobilities ten times higher than their amorphous counterparts.

Conclusions:

• The Mannich-elimination approach provides a versatile route to robust, highly crystalline 2D conjugated polymer materials.
• Crystallinity is a critical factor in determining charge transport efficiency in 2D PAVs.
• This work paves the way for advanced applications of 2D conjugated polymers in various fields.