Oxidation Process and Addition of Zn and Te Lead to the Enhancement of Thermoelectric Figure of Merit in p-Type Bi₂Te₃

To date, Bi₂Te₃-based systems are the most promising thermoelectric materials near room temperature for Peltier cooling and energy harvesting. Further improvement of the thermoelectric figure of merit <i>zT</i> is required to broaden the application of Bi₂Te₃-based thermoelectrics. In this study, we investigated the critical role of oxidation in the thermoelectric performance of p-type Bi_0.45Sb_1.55Te₃ and proposed a way to improve the performance. Impurity oxides inevitably formed during the fabrication processes of constituent elements, leading to lowered mobility. To solve this problem, an oxygen getter element, Zn, was added to capture the oxygen from the Bi_0.45Sb_1.55Te₃ matrix to increase the mobility. Moreover, the formed byproduct ZnO effectively scattered heat-carrying phonons simultaneously. The control of the oxidation process and the addition of Zn and Te led to a 30% enhancement in the <i>zT</i> of Bi_0.45Sb_1.55Te₃ with the decoupling of improved electronic properties and reduced lattice thermal conductivity.