Rashba Effect Maximizes Thermoelectric Performance of GeTe Derivatives
Summary Advances in thermoelectrics are motivated by the innovation of thermoelectric theories. The Rashba effect, spin dependent band splitting, paves a new path to enhance thermoelectric performance. Herein, we investigate the Rashba effect in GeTe, in which the rhombohedral distortion provides a unique handle to examine the mechanism of the Rashba effect for tuning thermoelectric properties. Fundamentally, we discover that the Rashba effect originates from the specific atomic site displacement. Experimentally, Sn doped GeTe has a strong Rashba effect and yields an ultra high power factor, meanwhile additional Sb alloying effectively tunes the carrier concentration. Moreover, microstructure characterizations reveal that the co existence of grain boundaries, nanoprecipitates, and stacking faults significantly reinforces phonon scatterings and leads to an ultra low lattice thermal conductivity. Finally, a high figure of merit is achieved in Ge1 x ySnxSbyTe. The demonstrated benchmark figure of merit originated from the Rashba effect can provide a promising arena for enhancing thermoelectric performance in wide materials.