2D Piezoelectric Covalent Organic Frameworks: Construction, Characterization, and Potential Applications

Area of Science:

• Materials Science
• Nanotechnology
• Chemistry

Background:

• 2D piezoelectric covalent organic frameworks (2D p-COFs) integrate precise structure, symmetry breaking, and electromechanical properties.
• Unlike inorganic materials and polymers, 2D p-COFs utilize ordered, noncentrosymmetric structures for efficient energy conversion, offering tunable properties, porosity, and stability.

Purpose of the Study:

• To review the fundamental principles of piezoelectricity in 2D p-COFs.
• To explore synthesis strategies, particularly fluorinated side-chain functionalization, for enhanced piezoelectric performance.
• To discuss the characterization and diverse applications of 2D p-COFs in energy harvesting, catalysis, and sensing.

Main Methods:

• Grafting fluorine-substituted alkyl chains onto COFs to induce dipole alignment and spontaneous polarization.
• Designing hybrid systems to optimize piezoelectric coefficients and open-circuit voltages.
• Reviewing synthesis techniques and characterization methods for 2D p-COFs.

Main Results:

• Demonstrated efficient mechanical-to-electrical energy conversion in 2D p-COFs.
• Achieved significant piezoelectric coefficients and high open-circuit voltages in nanogenerators through fluorination and hybrid designs.
• Highlighted the potential for tunable structures, permanent porosity, and stability.

Conclusions:

• 2D p-COFs represent a promising class of materials for piezoelectric applications.
• Advances in synthesis and design have led to high-performance nanogenerators.
• Future research should address challenges in scalability and long-term stability for broader adoption.