Improved Thermoelectric Performance of Monolayer HfS₂ by Strain Engineering

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Two-dimensional transition metal dichalcogenides exhibit tunable thermoelectric properties under strain.
• Strain engineering is a key strategy to optimize energy band degeneracy for improved thermoelectric performance.

Purpose of the Study:

• To investigate the impact of biaxial strain on the thermoelectric properties of 1T-phase monolayer HfS2.
• To determine the optimal strain conditions for maximizing the figure of merit (ZT) in both n-type and p-type HfS2.

Main Methods:

• First-principles calculations were employed to study phonon, electronic, and thermal properties.
• Boltzmann transport equations were integrated to analyze thermoelectric performance.
• Biaxial strain was systematically applied to the monolayer HfS2 structure.

Main Results:

• Unstrained monolayer HfS2 shows a maximum ZT of 1.09 for n-type and 0.09 for p-type.
• At 6% strain, n-type HfS2 achieves a maximum ZT of 2.29 with reduced thermal conductivity and maintained power factor.
• At 7% strain, p-type HfS2 demonstrates a significantly enhanced maximum ZT of 3.35 due to a substantial increase in power factor.

Conclusions:

• Biaxial strain is highly effective in improving the thermoelectric performance of monolayer HfS2.
• P-type monolayer HfS2 shows particularly promising results, with a ZT value reaching 3.35 under 7% strain.
• The findings provide valuable data for experimental exploration of strained HfS2 for thermoelectric applications.