Electronic Structure and Transport Properties of Skutterudite CoSb3

We report on the electronic structure and electronic transport properties of skutterudite CoSb3 based on density functional theory utilizing the nonequilibrium Green’s function method. CoSb3 has a non-parabolic (linear) dispersion relation near the top of the valence band, and the hole effective mass is much smaller than the electron effective mass. This is the reason for the characteristic property that hole mobility is higher than electron mobility. This is completely different from that of ordinary semiconductors. The four-membered ring of Sb, which is one of the features in the crystal structure, is important in relation to the electronic structure and electronic properties. The relation of these crystal structure features to the electron transport properties is discussed. Then, the optimization of thermoelectric properties is discussed based on the chemical potential dependence of thermoelectric properties.