Bilayer MSe₂ (M = Zr, Hf) as promising two-dimensional thermoelectric materials: a first-principles study

Area of Science:

• Materials Science
• Condensed Matter Physics
• Solid State Chemistry

Background:

• Two-dimensional transition metal dichalcogenides (TMDs) are actively researched for their unique properties.
• Experimental synthesis of 2D MSe2 (M = Zr, Hf) thin films motivates further theoretical investigation.

Purpose of the Study:

• Investigate electronic, thermal, and thermoelectric transport properties of 1T-phase MSe2 (M = Zr, Hf) bilayers.
• Evaluate their potential as next-generation thermoelectric materials.

Main Methods:

• First-principles calculations.
• Boltzmann transport theory.

Main Results:

• Bilayer ZrSe2 and HfSe2 are indirect band gap semiconductors.
• Degenerate conduction bands and stair-like DOS contribute to a high n-doped power factor.
• Low lattice thermal conductivity observed due to low phonon frequencies and mode coupling.
• Predicted maximum figure of merit (ZT) at room temperature: 1.84 for ZrSe2 and 3.83 for HfSe2 bilayers (n-type).

Conclusions:

• Bilayer ZrSe2 and HfSe2 exhibit promising thermoelectric properties.
• These materials demonstrate superior performance compared to their bulk counterparts.
• Bilayer MSe2 holds potential for advanced thermoelectric applications.