Hydrostatic pressure (P) has been regarded as an effective approach to improve the performance of thermoelectric materials. Although a positive correlation between its thermoelectric performance and pressure has been demonstrated experimentally for CuInTe2, the underlying physical mechanism remains unclear. Herewith, we investigate the inherent mechanism of hydrostatic pressure-induced electron-thermal transport properties and thermoelectric conversion efficiency for CuInTe2. It is demonstrated that the pressure limits the thermal transport behavior of heat-carrying phonons by changing phonon dispersion, where the broadening of the low-lying phonon bandwidth caused by the compression promotes the dominance of the four-phonon (4ph) scattering mechanism, especially at high temperatures. In addition, the power factor has achieved a huge net increase through the convergence of the valence band edge despite the presence of strong coupling between electron transport parameters. Such bidirectional optimization gives rise to a remarkable enhancement of thermoelectric conversion efficiency. Our work highlights the significant effect of pressure-induced 4ph interaction in CuInTe2, which brings deeper insights into the behavior of thermoelectric materials under extreme pressure environments.

The authors gratefully thank the support of the National Natural Science Foundation of China (No. 52072188) and the Program for Science and Technology Innovation Team in Zhejiang (No. 2021R01004). And we acknowledge the Institute of High-pressure Physics of Ningbo University for its computational resources.