Thermoelectric performance of MoSi2As4 monolayer is investigated using density functional theory combined with Boltzmann transport theoy. The maximal power factors of n- and p-type by PBE (HSE06) functional are 7.73 (48.31) and 32.84 (30.50) mW m-1 K-2 at the temperature of 1200 K, respectively. The lattice thermal conductivity is less than 30 W m-1 K-1 above 800 K. The thermoelectric figure of merit can reach 0.33 (0.58) and 0.90 (0.81) using PBE (HSE06) functional for n- and p-type under appropriate carrier concentration at 1200K, respectively. Thus, the p-type MoSi2As4 monolayer is predicted to be a potential candidate for high-temperature thermoelectric applications.

Based on the first-principles of density functional theory and Boltzmann transport theory, we report two-dimensional (2D) α-Se2Te monolayer to be a high-performance medium temperature p-type thermoelectric material with low lattice thermal conductivity (κ l ), high power factor (PF) and high dimensionless figure of merit (ZT). At the temperature of 700 K, PF is up to 3.77 and 11.5 mW m−1 K−2, ZT is up to 0.55 and 1.91 in appropriate doping level for n- and p-types, respectively, and k l is as low as 2.09 W m−1 K−1. We also examine the effect of spin-orbital coupling (SOC) on the carrier transport and find that with SOC, PF and hence ZT will be reduced significantly due to the reduced band gap. The higher PF of p-type than that of n-type is evidently due to the flatter valence band edge than conduction band edge. Low k l is inevitably attributed to the strong lattice anharmonicity.

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Thermoelectric transport properties of two-dimensional (2D) layered NaCuX (X=S, Se) are investigated by employing first-principles based Boltzmann transport theory. The single quintuple layer NaCuX have relative large Seebeck coefficient (S),...