Intrinsic piezoelectricity of 2D violet phosphorene

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Violet phosphorene (VP) possesses excellent electron transport properties, suggesting potential for piezoelectric devices.
• However, VP materials typically lack the inherent ionic polarity required for piezoelectric effects.

Purpose of the Study:

• To investigate the piezoelectric capacity of violet phosphorene (VP) nano-sheets.
• To determine the in-plane and out-of-plane piezoelectric response of VP.

Main Methods:

• Density Functional Theory (DFT) calculations to identify inherent dipoles in VP.
• Piezoelectric Force Microscopy (PFM) to measure piezoelectric coefficients (d33 and d31).
• Experimental application of electric field excitation (-18 V to +18 V) to observe piezoelectric hysteresis loops.

Main Results:

• VP nano-sheets demonstrate distinct in-plane and out-of-plane piezoelectricity.
• A direct piezoelectric response and hysteresis loops were observed in monolayer VP.
• DFT calculations confirmed the presence of intrinsic dipoles within VP.
• PFM measurements on 17.6 nm thick VP showed d33 up to 12.65 pm V⁻¹ and d31 up to 1.03 pm V⁻¹.
• Piezoelectric properties were found to decrease with increasing VP thickness.

Conclusions:

• Violet phosphorene is a novel material with intrinsic piezoelectric properties, suitable for piezoelectric applications.
• The study establishes VP as a promising candidate for next-generation piezoelectric devices.
• Understanding the thickness-dependent piezoelectric behavior is crucial for optimizing VP-based device performance.