Tuning the electronic structure of rhombohedral and cubic GeTe for thermoelectric application: Influence of molybdenum doping.

Substitutional doping to engineer the electronic structure of materials has received high prominence in developing high performance thermoelectric materials. Herein, we study the effect of molybdenum doping on the electronic structure of GeTe and provide insights into the observed enhancement of thermoelectric performance. We discover that Mo doping has a huge impact on the band structure of both rhombohedral and cubic phase of GeTe. In addition to increasing the band gap, Mo doping causes huge increase in the density of states near the Fermi level. We also notice convergence of valence sub-bands and hyperconvergence of conduction sub-bands besides introduction of multiple carrier valleys promoting transport in both p and n-type materials. These features undoubtedly make Mo doping a beneficial approach in the development of lead free GeTe thermoelectrics. [Display omitted] • First principles study on electronic structure engineering of GeTe by doping Mo. • Large increase in band gap caused by Mo doping in both rhombohedral and cubic phases. • Valence band convergence and generation of multiple valleys leading to increase in Nv. • First report on hyperconvergence of conduction band induced by Mo doping in GeTe. • Study reveals the potential to be developed into high performing p-type as well as n-type TE material. [ABSTRACT FROM AUTHOR]