Half-Heusler thermoelectric materials: Towards the decoupling between electrons and phonons

Among the state-of-the-art thermoelectric (TE) materials, half-Heusler (HH) compounds have many advantages such as their high power factor, mechanical and chemical stability, employment of non-toxic and abundant elements, etc. However, these advantages haven’t been translated into practical applications because of insufficient reduction of lattice thermal conductivity, thus making the overall TE performance of HH compounds less competitive than other materials (such as Bi₂Te₃). In this talk, I will introduce the electronic and phononic transport features of HH compounds, and their responses to the microstructural modifications. More importantly, I will emphasize decoupling the coupled transport of electrons and phonons by using a variety of strategies such as manipulating the phonon group velocity and mitigating the grain boundaries scattering. Novel synthesis approaches will also be discussed to effectively reduce the lattice thermal conductivity such as high-pressure sintering.