A Delamination Strategy for Thinly Layered Defect-Free High-Mobility Black Phosphorus Flakes

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Black phosphorus (BP) possesses unique electronic and photonic properties, making it crucial for novel electronics and optoelectronics.
• Scalable synthesis of large, pristine BP flakes is a significant challenge despite progress in preparing thin flakes.

Purpose of the Study:

• To demonstrate an efficient and scalable electrochemical delamination strategy for producing large, defect-free black phosphorus flakes.
• To characterize the properties of BP flakes produced by this method and their performance in electronic devices.

Main Methods:

• Utilized an electrochemical delamination strategy involving intercalation of various cations in non-aqueous electrolytes.
• Employed tetra-n-butylammonium cations and bisulfate anions to promote exfoliation.
• Fabricated bottom-gate and bottom-contact field-effect transistors using the synthesized BP flakes.

Main Results:

• Achieved a high exfoliation yield of up to 78% and produced large BP flakes up to 20.6 μm.
• Synthesized few-layer BP flakes exhibiting high hole mobility (252±18 cm² V⁻¹ s⁻¹) and an on/off ratio of (1.2±0.15)×10⁵ at 143 K under vacuum.
• Demonstrated the effectiveness of the interplay between specific cations and anions in the delamination process.

Conclusions:

• The developed electrochemical delamination method is efficient and scalable for producing high-quality black phosphorus flakes.
• This technique holds significant potential for the advancement of black phosphorus-based composites and optoelectronic devices.
• The method overcomes previous limitations in synthesizing large, pristine BP flakes for advanced applications.