First-principles study of electronic structures and thermoelectric properties of 2H–CuAlO2

• 2H–CuAlO2 properties are theoretically studied using first principles calculations.
• 2H–CuAlO2 is an indirect gap material with the gap of around 2.2 eV.
• The rigid band and constant scattering time are used in thermoelectric calculation.
• ZT at 680 K has maximum values at around 0.007 (p-type) and 0.0035 (n-type).
• 2H–CuAlO2 has a high ZT at metallic carrier concentration and high temperature.

Electronic structures and thermoelectric properties of delafossite 2H–CuAlO2 have been theoretically investigated using first principles calculations and Boltzmann transport equation. The delafossite 2H–CuAlO2 exhibits an indirect gap of 2.2 eV and a direct gap of 3.1 eV. As the temperature increases, the electrical conductivity increases but the Seebeck coefficient decreases. However, the power factor tends to increase with temperature and dramatically increases in the case of high carrier concentration when the doping level is located near the valence band. It is also found that the dimensionless figure of merit, ZT  , increases with increasing temperature. At T=680 KT=680 K, the calculated ZT are 0.007 for p-type doping and 0.0035 for n-type doping. These maximum ZT   are obtained at the carrier concentration of approximately 5.0×1021 cm−35.0×1021 cm−3 and 1.0×1021 cm−31.0×1021 cm−3 for p-type and n-type dopings, respectively.