First-Principle Theory Study on Electronic Structure of Ca3Co2O6 and Cu-Doped

The relation among electronic structure, chemical bond and thermoelectric property of Ca₃Co₂O₆ and Cu-doped is studied by first-principle theory. The results indicate that the highest valence band (HVB) and the lowest conduction band (LCB) are mainly contributed from Co3d, Cu3d and O2p atomic orbitals and that 1D Co-O chains along c axis play important role in electric property of Ca₃Co₂O₆ and Cu-doped. The property of semiconductor is shown from the gap between HVB and LCB and impurity energy level comes out after Cu-doped and the gap becomes narrower which will increase the mobility of carriers and then decrease the resistivity. The metal characteristics of Cu-doped one are stronger than those of Ca₃Co₂O₆. The thermoelectric property should be improved from adding Cu element into the system of Ca₃Co₂O₆.