Improved Thermoelectric Performance of p-Type Argyrodite Cu8GeSe6 via the Simultaneous Engineering of the Electronic and Phonon Transports

Guided by the concept of phonon-liquid electron-crystal, many n-type argyrodite compounds have been developed as candidates for thermoelectric (TE) materials. In recent years, the p-type Cu8GeSe6 (CGS) compound has attracted some attention in TEs due to the presence of very strong atomic vibrational arharmonicity inside the sublattice, which is caused by the weak bonding between Cu ions and [GeSe6](8-). However, its TE performance is still poor, with a ZT value of only 0.2 at 623 K. Therefore, in this work, we propose to engineer both the electronic and phonon transports in CGS by incorporating the species In2Te3. This strategy tunes the carrier concentration and at the same time increases the phonon scattering on the point defects (In-Ge, In-interstitial, and Te-Se) and randomly distributed tetrahedra ([InSe4](5-) and [GeTeSe3](4-)). As a result, the phase transformation at 329 K in CGS is eliminated, and the peak ZT value is enhanced from 0.27 for CGS to similar to 0.92 for (Cu8SnSe6)(0.9)(In2Te3)(0.1) at 774 K; this thus proves that the incorporation of In2Te3 in CGS is an effective way of regulating its TE performance.

Automated summary

In this study, the electronic and phonon transports in Cu8GeSe6 compound were engineered by incorporating In2Te3 species, resulting in improved thermoelectric performance.