Two-dimensional square-Au₂S monolayer: A promising thermoelectric material with ultralow lattice thermal conductivity and high power factor*

Abstract

The search for new two-dimensional (2D) harvesting materials that directly convert (waste) heat into electricity has received increasing attention. In this work, thermoelectric (TE) properties of monolayer square-Au2S are accurately predicted using a parameter-free ab initio Boltzmann transport formalism with fully considering the spin–orbit coupling (SOC), electron–phonon interactions (EPIs), and phonon–phonon scattering. It is found that the square-Au2S monolayer is a promising room-temperature TE material with an n-type (p-type) figure of merit ZT = 2.2 (1.5) and an unexpected high n-type ZT = 3.8 can be obtained at 600 K. The excellent TE performance of monolayer square-Au2S can be attributed to the ultralow lattice thermal conductivity originating from the strong anharmonic phonon scattering and high power factor due to the highly dispersive band edges around the Fermi level. Additionally, our analyses demonstrate that the explicit treatments of EPIs and SOC are highly important in predicting the TE properties of monolayer square-Au2S. The present findings will stimulate further the experimental fabrication of monolayer square-Au2S-based TE materials and offer an in-depth insight into the effect of SOC and EPIs on TE transport properties.

Adaptive genetic algorithm-based design of gamma-graphyne nanoribbon incorporating diamond-shaped segment with high thermoelectric conversion efficiency

“…[1] Thermoelectric technology is one of the most potential candidates for new generation energy conversion, which could recover waste heat from energy consumption (e.g., automobile exhaust, exhaust gas from factory boilers) to available electricity. [2,3] For maximizing the thermoelectric performance, the material should host low thermal conductivity (κ e + κ ph ), high electrical conductivity (σ ), and large Seebeck coefficient (S). [4] The thermoelectric conversion efficiency could be evaluated by a dimensionless thermoelectric figure of merit (ZT ): ZT = σ S 2 T /(κ e + κ ph ).…”