Low lattice thermal conductivity and high figure of merit in p-type doped K3IO* *Project supported by the National Natural Science Foundation of China (Grant Nos. 11974302, 11774396, and 11704322) and the Shandong Natural Science Funds for Doctoral Program, China (Grant No. ZR2017BA017).

Abstract

Based on first-principles calculations, Boltzmann transport equation and semiclassical analysis, we conduct a detailed study on the lattice thermal conductivity κ L, Seebeck coefficient S, electrical conductivity σ, power factor S 2 σ and dimensionless figure of merit, zT, for K3IO. It is found that K3IO exhibits relatively low lattice thermal conductivity of 0.93 W⋅m−1⋅K−1 at 300 K, which is lower than the value 1.26 W⋅m−1⋅K−1 of the classical TE material PbTe. This is due to the smaller phonon group velocity ν g and smaller relaxation time τλ . The low lattice thermal conductivity can lead to excellent thermoelectric properties. Thus maximum zT of 2.87 is obtained at 700 K, and the zT = 0.41 at 300 K indicate that K3IO is a potential excellent room temperature TE material. Our research on K3IO shows that it has excellent thermoelectric properties, and it is a promising candidate for applications in fields in terms of thermoelectricity.