Significant first-principles electron-phonon coupling effects in the and half-Heusler thermoelectrics
Phys. Rev. B 113, 115203 – Published 6 March, 2026
DOI: https://doi.org/10.1103/ss62-r49n
Abstract
Half-Heusler (hH) compounds are currently considered promising thermoelectric (TE) materials owing to their favorable thermopower and electrical conductivity. Accurate estimates of their TE performance are therefore highly desirable and require a detailed microscopic understanding of the mechanisms that limit carrier transport. To enable such estimations, we carry out comprehensive first-principles computations of the electron-phonon interactions in two hH semiconductors (LiZnAs and ScAgC). Our study first investigates their electron and phonon dispersions and then examines the temperature-induced renormalization of the electronic states within the nonadiabatic Allen-Heine-Cardona formalism. We then solve the Boltzmann transport equation (BTE) both iteratively and within multiple relaxation-time approximations (RTAs) to evaluate the carrier transport properties. Phonon-limited electron and hole mobilities computed using the linearized self-energy and momentum RTAs (SERTA and MRTA) are compared with the iterative BTE (IBTE) results. The electrical transport coefficients for TE performance are subsequently evaluated under these two RTA schemes and compared with constant RTA (CRTA) results. The lattice thermal conductivity, determined from phonon-phonon interaction, is further reduced through nanostructuring. In bulk form, LiZnAs (ScAgC) attains a maximum figure of merit of (0.78) at 900 K for an electron concentration of under the MRTA. For a 20-nm nanostructured sample, the corresponding increase to (1.0). The remarkably high achieved through inherently present phonon-induced electron scattering effects, combined with grain-boundary engineering, opens a promising path for discovering highly efficient and accurate next-generation hH TEs.
