Enhanced Thermoelectric Performance in Black Phosphorene via Tunable Interlayer Twist

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Two-dimensional (2D) materials offer tunable properties via moiré superlattices.
• Black phosphorene is a promising 2D material with unique electronic and thermal characteristics.

Purpose of the Study:

• Investigate the angle-dependent thermoelectric properties of twisted bilayer black phosphorene (tbBP).
• Explore the potential of tbBP for thermoelectric applications by optimizing twist angles.

Main Methods:

• First-principles calculations were employed to simulate thermoelectric properties.
• Analyzed the electronic band structure and phonon scattering mechanisms.

Main Results:

• Achieved significantly enhanced Seebeck coefficient and power factor in p-type tbBP due to multi-valley electronic states and flat moiré bands.
• Observed very low lattice thermal conductivity (4.51 W m⁻¹ K⁻¹ at 300 K) attributed to strong anharmonic phonon scattering.
• Reported a maximal thermoelectric figure of merit (ZT) of 0.57 at 300 K and 1.06 at 500 K for p-type 10.11° tbBP along the armchair direction.
• Demonstrated a ~40-fold increase in room-temperature ZT along the zigzag direction for a twist angle near 70.68° compared to pristine black phosphorene.

Conclusions:

• Twisted bilayer black phosphorene presents a tunable platform for enhancing thermoelectric performance.
• The unique electronic and phononic properties induced by moiré patterns position tbBP as a strong candidate for eco-friendly thermoelectric devices.