First principles study on the thermoelectric properties of delafossite compounds

Thermoelectric materials should have the coexistence of large power factor PF = σS² and low thermal conductivity for the enhancement of thermoelectric efficiency. It is however difficult to obtain good thermoelectric materials because the power factor is maximized at a certain doping level due to the relationship between the Seebeck coefficient and the electrical conductivity. We proposed that the ``pudding mold type band”, which has a flat portion at a band edge gives rise to large power factor [1,2].

Recently, PtCoO₂ has been found to possess extremely small resistivity and high mobility.[3] The electronic band structure of PtCoO₂ exhibits the pudding mold type shape, which suggests the possibility to possess large thermoelectric performance. We study the thermoelectric properties of PtCoO₂ from first principles calculations within the Boltzmann transport theory and the rigid band approximation. It is found that the power factor can be enhanced due to high mobility by controlling the carrier concentration.

[1] K. Kuroki and R. Arita, J. Phys. Soc. Jpn. 76, 083707 (2007).
[2] H. Usui and K. Kuroki, J. Appl. Phys. 121, 165101 (2017).
[3] A.P. Mackenzie, Rep. Prog. Phys. 80, 032501 (2017).