Theoretical insight into thermoelectric response of valleytronic semiconductor 1H-TiNBr monolayer

Thermal and electrical transport of valleytronic semiconductor 1H-TiNBr monolayer is investigated from first-principles based self-consistent transport theory. Lattice thermal conductivity is greatly reduced from 1.07 W ​m −1 ​K −1 to 0.60 ​W ​m −1 ​K −1 by quartic anharmonicity at room temperature. Electrical transport parameters including Seebeck coefficient, electrical conductivity and carrier thermal conductivity are precisely calculated with the scattering rates of individual carrier states, and the resultant Seebeck coefficient is much larger due to the multiple valence bands with close energy, and thereby power factor is larger for p-type doping at high carrier contents. The optimal peak and averaged thermoelectric figure of merit are 0.691 and 0.476 for p-type doping and 0.595 and 0.409 for n-type doping in the temperature range of 500 K to 700 ​K, shewing light on the critical necessary of the intrinsic quartic anharmonicity and multiple types of carrier scattering in dominating the TE performance.