Anomalous Thermoelectric Transport Phenomena from First-Principles Computations of Interband Electron–Phonon Scattering
Auteurs
Fedorova N.S., Cepellotti A., Kozinsky B.
Référence
Advanced Functional Materials, vol. 32, n° 36, art. no. 2111354, 2022
Description
The Seebeck coefficient and electrical conductivity are two central quantities to be optimized simultaneously in designing thermoelectric materials, and they are determined by the dynamics of carrier scattering. Here a new regime is uncovered where the presence of multiple electron bands with different effective masses, crossing near the Fermi level, leads to strong energy-dependent carrier lifetimes due to intrinsic electron–phonon scattering. In this anomalous regime, electrical conductivity decreases with carrier concentration, Seebeck coefficient reverses sign even at high doping, and power factor exhibits an unusual second peak. The origin and magnitude of this effect is explained using a general simplified model as well as first-principles Boltzmann transport calculations in recently discovered half-Heusler alloys. General design rules for using this paradigm to engineer enhanced performance in thermoelectric materials are identified.
