Impressive enhancement of thermoelectric performance in CuInTe₂ upon compression

Thermoelectric materials can directly generate electric power by converting waste heat, and the efficiency is appraised by the figure of merit zT. A high zT value larger than 3 is required to achieve comparable efficiency of the traditional heat engines. Despite great efforts over a century, the desired value of 3 is seemingly an upper limit and many existing thermoelectric materials have the zT values less than 1. If their zT values can be improved for several times to break through the upper limit, the energy revolution could be expected. Here, a p-type CuInTe₂ is chosen as an example to show the extremely important role of pressure played in enhancing the thermoelectric performance. Over 5 times increase of the zT value is realized by the application of pressure. Both the enhancement of the power factor and the reduction of the thermal conductivity account for this impressive enhancement. The former is due to the optimization of the carrier concentration and band structure, and the latter is attributed to the enhanced phonon anharmonicity. Our results offer an effective method to improve zT of the existing materials for the future technological applications.