Enhancing the thermoelectric performance of Janus MoSSe monolayer via pressure

Abstract

By combining first-principles computations with the semi-classical Boltzmann transport equations, a systematic investigation of the structural, electronic and thermoelectric properties of the MoSSe Janus monolayer is conducted under pressure. The monolayer semiconducting nature is indicated by the band gap value (E_g = 1.5 eV), which may be further tuned from 0.56 to 1.67 eV by applying pressure in the -3GPa to + 2GPa range. The figure of merit (ZT) for p (n)-type carriers at 300 K in the absence of pressure is computed to be 0.67 and 0.59. The power factor has enhanced from 16.59 (27.21) Wm⁻¹ K⁻² to 227.15 (159.50) Wm⁻¹ K⁻² for n (p)-type carriers by applying an external pressure of -1 GPa to the Janus monolayer. For n (p) -type doping at 300 K, the corresponding maximum value of ZT is 0.82 (0.78), which is 39% (14%) greater for n (p) type than for pure MoSSe Janus monolayer. When the pressure is increased to + 3 GPa, the value of ZT for n-type doping is further increased to 0.73, which is 24% higher than the value for pure monolayer. It is possible for a pure Janus monolayer to undergo n-type doping under pressure due to the shifting of the conduction band minima and valence band maxima. This study presents an attractive approach for manipulating the material thermoelectric properties through external pressure application.