The Electronic Transport Channel Protection and Tuning in Real Space to Boost the Thermoelectric Performance of Mg3+δSb2-yBiy near Room Temperature

Abstract

The optimization of thermoelectric materials involves the decoupling of the transport of electrons and phonons. In this work, an increased Mg1-Mg2 distance, together with the carrier conduction network protection, has been shown as an effective strategy to increase the weighted mobility (U=μm∗3/2) and hence thermoelectric power factor of Mg3+δSb2-yBiy family near room temperature. Mg3+δSb0.5Bi1.5 has a high carrier mobility of 247 cm2 V-1 s-1 and a record power factor of 3470 μW m-1 K-2 at room temperature. Considering both efficiency and power density, Mg3+δSb1.0Bi1.0 with a high average ZT of 1.13 and an average power factor of 3184 μW m-1 K-2 in the temperature range of 50-250°C would be a strong candidate to replace the conventional n-type thermoelectric material Bi2Te2.7Se0.3. The protection of the transport channel through Mg sublattice means alloying on Sb sublattice has little effect on electron while it significantly reduces phonon thermal conductivity, providing us an approach to decouple electron and phonon transport for better thermoelectric materials.