High Thermoelectric Power Factor in Intermetallic Co Si Arising from Energy Filtering of Electrons by Phonon Scattering
Abstract
Intermetallic compounds are usually poor thermoelectrics due to the high electronic densities of states at the Fermi level and concomitantly low Seebeck coefficients. However, intermetallic B 20 -type Co Si has been experimentally shown to attain remarkably large negative values of the Seebeck coefficient. We provide a theoretical explanation for this surprising fact using state-of-the-art first-principles calculations with explicit treatment of electron-phonon interactions. We find that the unique band structure of Co Si , which has both massless and heavy fermion bands near the Fermi level, facilitates strong scattering of the low-energy electrons by phonons into the heavy band, resulting in effective energy filtering and high thermal voltage. Our study predicts that a very large thermoelectric power factor of 80 μ W cm-1K-2 or higher is experimentally accessible in the 300 -600 K range and highlights a general principle for identifying intermetallic compounds with large thermopower.
- Publication:
-
Physical Review Applied
- Pub Date:
- February 2019
- DOI:
- 10.1103/PhysRevApplied.11.024017
- Bibcode:
- 2019PhRvP..11b4017X