Ultralow lattice thermal conductivity and thermoelectric properties in anti-MoS2 nanostructured Tl2SSe

Abstract

Discovering new two-dimensional (2D) materials and revealing the unique properties and potential applications are common pursuits within condensed matter physics and materials science. This study reported a novel metal-shrouded semiconductor anti-Tl2SSe monolayer (Tl2SSe monolayer featuring anti-MoS2 structures). The density functional theory combined with Boltzmann transport equations is used to investigate the thermal and thermoelectric properties of the anti-Tl2SSe monolayer. Due to low phonon group velocity (vg) and strong acoustic interband scattering, anti-Tl2SSe exhibits an ultralow lattice thermal conductivity (κL) of 0.54 W m−1 K−1 at room temperature. Further electron population and chemical bonding analysis show that the weak bonding of Tl leads to low vg and the antibonding interactions result in strong anharmonicity. Considering the electron–phonon coupling in electron transport, the anti-Tl2SSe monolayer exhibits a high zT value of 1.43 at 400 K. Additionally, the distinctive metal-shrouded structure of anti-Tl2SSe monolayer renders it a superior contact with electrode materials in device applications, which is rare in other 2D semiconductors. Our calculation results can provide a new paradigm in the thermoelectric material design.