DFT insight into tuning electron-phonon transmission and thermoelectric transport in nanoscale GeTe devices: effects...

Thermoelectric materials have received much attention for their ability to directly convert heat into electricity for energy-conversion applications. This work presents a complete study of the effect of antimony (Sb) substitutional doping on the thermoelectric transport properties of a GeTe system based on the DFT-NEGF framework. In this study, we investigated three different doping concentrations by substituting Ge atoms with Sb atoms, namely, 1Sb-doped, 2Sb-doped, and 3Sb-doped GeTe systems. The incorporation of Sb atoms dramatically changes the local atomic structure and electronic environment of the GeTe monolayer, which leads to remarkable changes in charge distribution, electronic structure and thermoelectric transport behaviour. To evaluate the thermoelectric response, two-probe device models are constructed for pristine and doped GeTe monolayers, and transport parameters such as electrical conductance, Seebeck coefficient, thermal conductivity, and figure of merit (ZT) are calculated. The results show that Sb substitution enhances the thermoelectric performance of GeTe, with the 2Sb-doped configuration exhibiting the highest ZT value of about 7.2 at 700 K. These findings demonstrate that Sb substitutional doping is an effective approach for improving the thermoelectric efficiency of two-dimensional GeTe-based devices.