  Enhancing band convergence is an effective way to optimize the thermoelectric
(TE) properties of materials. However, the temperature-induced band
renormalization is commonly ignored. By employing the recently-developed
electron-phonon renormalization (EPR) method, the nature of band
renormalization in half-Heusler (HH) compounds TiCoSb and NbFeSb is revealed,
and the key factors for temperature-induced conduction band convergence in HH
are found out. Using these as the screening criteria, 3 out of 274 HHs (TiRhBi,
TiPtSn, NbPtTl) are then stood out from our MatHub-3d database. Taking TiPtSn
as the example, it shows the conduction band convergence at mid-high
temperature, and further resulting in enhanced Seebeck coefficient S: e.g., at
600 K with electron concentration 10^20 cm^-3, the predicted S with and without
renormalized band is 352.83 uV/K and 289.52 uV/K, respectively. Herein, the
former is closer to our measurement value of 338.79 uV/K. Besides, the
effective masses obtained from calculation and experiment are both enlarged
with temperature, indicating the existence of band convergence. Our work
demonstrates for the first time the significance of adding the temperature
effect on electronic structure in the design of potential high-performance TE
materials.
