Power factor enhancement in Zn-doped Na0.8CoO2

The thermoelectric properties of Na0.8ZnxCo1−xO2/(ZnO)y (x ≤ 0.01, 0 ≤ y ≤ 0.14) have been systematically investigated. The results suggest that doping divalent Zn ions within solubility limit x* ∼ 0.01 leads to simultaneous reduction in resistivity and enhancement of thermopower. Analysis of the results show that the reduction of resistivity may be attributed to improved mobility of carriers, while the enhancement of thermopower may originate from the geometric relaxation of distorted CoO6 octahedra caused by partial Zn substitution, leading to a narrower band width in the strongly correlated environment, consequently resulting in a remarkable 20% improvement in power factor.

► We investigate the high-temperature thermoelectric properties of Zn-doped Na0.8CoO2. ► 1% substitution of Zn for Co leads to simultaneous enhancement of thermopower and reduction in resistivity. ► ∼20% improvement in power factor has been achieved.