Quantum mechanics

Raman spectroscopy

Delocalized electron

Materials science

Entropy (arrow of time)

Anharmonicity

Thermoelectric effect

Phonon

Seebeck coefficient

Thermoelectric materials

Thermodynamics

Physics

Optics

Condensed matter physics

Figure of merit

Electron

Optoelectronics

Science

The high-entropy concept provides extended, optimized space of a composition, resulting in unusual transport phenomena and excellent thermoelectric performance. By tuning electron and phonon localization, we enhanced the figure-of-merit value to 2.7 at 750 kelvin in germanium telluride–based high-entropy materials and realized a high experimental conversion efficiency of 13.3% at a temperature difference of 506 kelvin with the fabricated segmented module. By increasing the entropy, the increased crystal symmetry delocalized the distribution of electrons in the distorted rhombohedral structure, resulting in band convergence and improved electrical properties. By contrast, the localized phonons from the entropy-induced disorder dampened the propagation of transverse phonons, which was the origin of the increased anharmonicity and largely depressed lattice thermal conductivity. We provide a paradigm for tuning electron and phonon localization by entropy manipulation, but we have also demonstrated a route for improving the performance of high-entropy thermoelectric materials.

High figure-of-merit and power generation in high-entropy GeTe-based thermoelectrics