Ultra-low lattice thermal conductivity and high figure of merit for Janus MoSeTe monolayer: a peerless material for high temperature regime thermoelectric devices

The discovery of 2-D Janus materials has accelerated the research and development of novel nanodevices for numerous applications. Owing to its unique properties of structural asymmetry, the 2D Janus monolayers are extensively expedited for an optoelectronic, piezoelectric, thermoelectric behavior of the materials. Motivated with this, we have explored the thermoelectric behavior of Janus MoSeTe monolayer using an ab-initio technique. Moreover, we have calculated the electronic, vibrational, and transport parameters using density-functional theory, density functional perturbation theory and Boltzmann transport equations, respectively. To get an accurate calculation, the precise scattering time has been estimated at various temperatures using the deformation potential theory, instead of using constant relaxation time. In addition to it, the lattice thermal conductivity which is a crucial parameter to explore the thermoelectric behavior is also calculated. Interestingly, we have observed an ultra-low lattice thermal conductivity (0.095 Wm $$^-1$$ K $$^-1$$ at room temperature to 0.02 Wm $$^-1$$ K $$^-1$$ at 1200 K). Also, the sufficiently high thermoelectric figure of merit (around 3) makes this material promising for thermoelectric applications under high-temperature regimes.