Highly adjustable piezoelectric properties in two-dimensional LiAlTe₂by strain and stacking

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Two-dimensional (2D) piezoelectric materials are crucial for developing efficient piezoelectric nanogenerators.
• Existing 2D materials often have limitations in their piezoelectric performance or tunability.
• Understanding the fundamental piezoelectric properties of novel 2D materials is essential for device applications.

Purpose of the Study:

• To systematically investigate the piezoelectric properties of the 2D LiAlTe₂ monolayer.
• To explore the tunability of these properties under external strain and different stacking configurations.
• To assess the potential of 2D LiAlTe₂ for applications in piezoelectric nanogenerators and micro-nano devices.

Main Methods:

• First-principles calculations were employed to study the intrinsic piezoelectric properties of 2D LiAlTe₂.
• The effects of uniaxial strain on piezoelectric coefficients (d₁₁ and d₃₁) were systematically analyzed.
• The influence of different stacking orders (AA and AB) and layer numbers on piezoelectric performance was investigated.

Main Results:

• The 2D LiAlTe₂ monolayer exhibits significant in-plane (d₁₁ = 3.73 pm V⁻¹) and out-of-plane (d₃₁ = 0.97 pm V⁻¹) piezoelectric coefficients.
• Piezoelectric coefficients are highly tunable: d₁₁ dramatically changes with strain, reaching 7.80 pm V⁻¹ with 2% stretching.
• Stacking significantly enhances piezoelectricity: AB stacking in four layers boosts d₁₁ to 18.05 pm V⁻¹, while AA stacking enhances d₃₁ to 3.32 pm V⁻¹.

Conclusions:

• 2D LiAlTe₂ possesses excellent and highly tunable piezoelectric properties, surpassing some existing 2D materials like MoS₂.
• Strain and stacking offer effective methods to optimize piezoelectric coefficients for specific device requirements.
• The tunable nature of 2D LiAlTe₂ makes it a promising candidate for next-generation piezoelectric nanogenerators and micro-nano devices.