Programmable Piezoelectricity of 2D Hexagonal Boron Nitride via Defect Engineering

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Piezoelectricity in 2D hexagonal boron nitride (hBN) is vital for advanced functional devices.
• Tailoring the intrinsic piezoelectric properties of 2D hBN is crucial for optimizing device performance.

Purpose of the Study:

• To investigate the impact of defects on the piezoelectric properties of 2D hBN.
• To explore methods for tuning piezoelectricity in 2D materials through defect engineering.

Main Methods:

• Utilized Kelvin probe force microscopy to directly measure local piezoelectric potentials in defective 2D hBN.
• Employed high-throughput molecular dynamics simulations to analyze piezoelectric coefficients in numerous defective 2D hBN structures.
• Developed a machine learning-based method for inverse design of defective 2D hBN with specific piezoelectric properties.

Main Results:

• Introduced defects into monolayer hBN enhanced local piezoelectric potentials by approximately 20%.
• Defect structure design allows for continuous tuning of piezoelectric coefficients, including decreases and increases.
• Flexoelectric effects around defects significantly influence polarization (±50%) in stretched defective 2D hBN, explaining the tunability.
• Demonstrated the potential to extend this defect engineering strategy to other 2D materials like molybdenum disulfide.

Conclusions:

• Defect engineering provides a novel and effective approach to tailor the piezoelectric properties of 2D hBN and other 2D materials.
• This work deepens the understanding of piezoelectricity in defective 2D materials and offers a pathway for designing next-generation piezoelectric devices.