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

摘要

Motivated by the experimental synthesis of two-dimensional MSe2 (M = Zr, Hf) thin films, we set out to investigate the electronic, thermal, and thermoelectric transport properties of 1T-phase MSe2 (M = Zr, Hf) bilayers on the basis of first-principles calculations and Boltzmann transport theory. Both bilayer ZrSe2 and HfSe2 are indirect band gap semiconductors possessing degenerate conduction bands and stair-like-shaped DOS, which provide a high n-doped power factor. In combination with the low lattice thermal conductivity that originated from the low phonon frequency of acoustic modes and the coupling of acoustic modes with optical modes, the maximum figure of merits ZT at room temperature for n-type doping are predicted as 1.84 and 3.83 for ZrSe2 and HfSe2 bilayers, respectively. Our results suggest that bilayer conformation of ZrSe2 and HfSe2 are promising thermoelectric materials with superior performance to their bulk counterparts.