Prediction of structurally stable two-dimensional AuClO2 with high thermoelectric performance

Numerous two-dimensional (2D) materials have been reported to exhibit remarkable thermoelectric (TE) performances owing to their quantum confinement effects. However, the identification of ideal TE materials with a low thermal conductivity (kappa(L)) and high Seebeck coefficient (|S|) remains a formidable challenge due to their high coupling and inherent conflict. In this work, a new monolayer semiconductor AuClO2 with a balanced TE performance has been theoretically predicted by combining first-principles calculations with the Boltzmann transport equation. The results of phonon spectrum, molecular dynamic (MD) simulations, and mechanical property analyses suggest that AuClO2 features thermodynamic and mechanical stability. Strikingly, AuClO2 possesses an ultralow kappa(L) of 0.14 (0.45) W m(-1) K-1 along the a (b)-axis at 300 K, thanks to its low phonon group velocity (upsilon(ph)) and short phonon lifetime (tau(ph)). Furthermore, the flat valence bands of AuClO2 promote a high |S| under p-type doping, leading to large zT values in the range of 1.0-2.4 under different temperatures and even up to a maximum value of 2.35 at 900 K. This study offers a promising TE material for applications in fields such as thermal insulation and thermoelectric refrigeration, and provides theoretical guidelines for the design of high performance 2D TE materials.

Automated summary

In this study, a balanced thermoelectric performance of a new monolayer semiconductor AuClO2 has been theoretically predicted. It exhibits both thermodynamic and mechanical stability, with low thermal conductivity and high Seebeck coefficient. This provides a promising material for thermal insulation and thermoelectric refrigeration applications, and offers theoretical guidelines for the design of high-performance 2D thermoelectric materials.