Theoretical prediction of the AuXO ₂ (X = Cl,Br,I) monolayers as promising thermoelectric material

Abstract Using density functional theory and semi-classical Boltzmann transport theory, we have investigated the properties of AuXO 2 (X = Cl, Br, I) monolayer, including stability, elasticity, electronic and thermoelectric transport properties. These monolayers exhibit direct bandgap semiconductor behavior, with band gaps of 2.00, 1.70, and 1.43 eV, respectively. In addition, the flat valence bands of AuXO 2 promote a high ∣ S ∣ under p-type doping, resulting in a large power factor (at 800K, the power factors of AuClO 2 , AuBrO 2 and AuIO 2 along the Y direction are 0.32, 0.39 and 0.19 mWm −1 K −2 , respectively). Their low lattice thermal conductivities (0.69, 0.11, and 0.05 Wm −1 K −1 for AuClO 2 , AuBrO 2 , and AuIO 2 along the Y-direction at 800 K) are attributed to heavy atoms, weak interatomic bonds, and strong anharmonic phonon scattering. It is worth noting that compared to AuClO 2 and AuIO 2 , AuBrO 2 shows excellent thermoelectric performance under p-type doping, which is due to its high power factor and moderate thermal conductivity. At 800 K, the value of p-type AuBrO 2 ZT reaches 1.8 along the Y-direction. Our findings highlight that AuBrO 2 is a promising candidate for thermoelectric applications.