Ultrahigh zT from strong electron–phonon interactions and a low-dimensional Fermi surface
Prof. Yang-Yuan Chen’s group in collaboration with Dr. T.H. Wang, Prof. H.T. Jeng and Prof. C.L. Chen have successfully explored the Sb-Bi co-doped GeTe single crystal (Ge0.86Sb0.08Bi0.06)Te with an ultrahigh zT of 2.7 at 700 K and a record high device ZT of 1.41 in the temperature range of 300-773 K. The ultrahigh zT is attributed to the extremely low lattice thermal conductivity induced by strong electron-phonon (EP) interaction as revealed by the observed Kohn anomaly, through inelastic neutron scattering (INS) measurements. First-principles calculations further demonstrate that the remarkable EP interaction arises from the Fermi surface nesting featured in one-dimensional (double-walled) topology. Our finding unravels the ultrahigh-zT mechanism in GeTe-based materials, serving as an inspiring guidance toward high thermoelectric performance. The significant findings were published in high impact journal of “Energy and Environmental science” (IF=32.5).
Journal Links: https://doi.org/10.1039/D3EE04187E