Synergistic optimization of the thermoelectric properties of Zn0.98Al0.02O using high-pressure and high-temperature treatment.

Here, the thermal and electrical properties of Al doped ZnO were synergistically improved by using high temperature and high pressure (HPHT) technology. HPHT treatment to modulate its crystal structure and microstructure. We simulated this process using first-principles calculations and finite element analysis. Increasing the synthesis pressure improved the electrical and thermal properties. As the synthesis pressure increased, the band gap decreased, and the electrical properties were improved. HPHT also changed the microstructure, and full-spectrum phonon scattering provided the sample with a relatively low thermal conductivity. The sample synthesized at 4.5 GPa achieved a dimensionless figure of merit (zT) of 0.165 at 973 K. Compared to related literature, the synthesized Al doped ZnO showed better thermoelectric properties than previous achievements at the same temperature, showing that HPHT provides a promising method for improving its thermoelectric performance. • The grain size and band gaps of ZnO were effective optimized. • Partial high pressure features of ZnO have been captured to the ordinary pressure. • The whole synthesis procedure last only for 30 min. • High pressure can induce rich defects which are beneficial for thermal properties. [ABSTRACT FROM AUTHOR]