Electronic and thermoelectric properties of Janus AsSeX (X = Cl, Br, I) monolayers: A first-principles study

We have conducted a study on the electronic and thermoelectric characteristics of Janus AsSeX (X = Cl, Br, I) monolayers. To accomplish this, we employed a combination of density functional theory (DFT) and Boltzmann transport theory. Through our study, we observed that the Janus AsSeX monolayers possess excellent dynamic, thermal, and mechanical stabilities. Our results reveal that AsSeCl, AsSeBr, and AsSeI are indirect band gap semiconductors with bandgaps of 2.10 eV, 1.87 eV, and 1.85 eV, respectively. Following the value of the B/G and v, we observe that Janus AsSeCl displays brittle property, whereas Janus AsSeBr and AsSeI exhibit ductile characteristics. We have also calculated the lattice thermal conductivity of these materials at room temperature, which are 1.87 Wm−1K−1, 3.80 Wm−1K−1, and 2.63 Wm−1K−1 for AsSeCl, AsSeBr and AsSeI, respectively. Furthermore, we have extracted thermal transport parameters, including the phase volume space group velocity, scattering rate, Grüneisen parameter, and group velocity, and carried out an in-depth analysis of their underlying mechanisms. Finally, we predict ZT values of 1.55, 0.95, and 1.11 for the p-type doping of Janus AsSeCl, AsSeBr, and AsSeI monolayers at 700 K, indicating that Janus AsSeCl and AsSeI monolayers are potential thermoelectric materials with high ZT values.