ThermoelectricPerformance of Janus Monolayer ZnGeSTefrom First-Principles Based Self-Consistent Transport Theory

Thermal and electrical transport properties of Janus monolayer ZnGeSTe are investigated using first-principles-based self-consistent transport theory. The temperature-driven phonon dispersion and lattice thermal conductivity (κ_l) are evaluated up to the quartic anharmonicity, and consequently, the κ_l is reduced by 42.36% upon quartic anharmonicity at room temperature. The Seebeck coefficient (<i>S</i>), electrical conductivity (σ), and carrier thermal conductivity (κ_e) are calculated by considering individual carrier lifetimes, and consequently, due to the convergence and dispersion of multiple conduction bands, the large Seebeck coefficient (<i>S</i>) and the high electron mobility contribute to a higher power factor (PF = <i>S</i>²σ) for n-type doping. The optimal figure of merit (zT = PF/(κ_e + κ_l)) monotonically increases with the temperature, and the peak and average zT values are up to 1.16 and 0.79 in the operating temperature range of 500–800 K for n-type doping.