Understanding pressure-driven thermoelectric properties of PdP₂ and PdAs₂ nanowires via band engineering

In the race of searching for alternative clean and sustainable energy sources, thermoelectric materials have shown potential hope by converting low-grade waste heat into electricity. The efficiency of thermoelectric devices is characterized by power factor or ZT. Therefore, enhancing ZT in nanowires for the thermoelectric application is highly desired. In recent work, we propose semi-metallic nanowire with asymmetry density of states near the Fermi energy as an alternative class of thermoelectric materials. We have considered the pentagonal structure of PdP₂ and PdAs₂ nanowires (NWs) and confirmed its dynamical stability by the phonon dispersion study. The PdX₂ structure shows the transition from semiconducting to semi-metallic behaviour at a compressive strain of 8% within sustainable pressure of 0.2~0.3GPa. The semi-metallic behaviour with the asymmetric density of states near the Fermi energy boosts Seebeck co-efficient value and therefore, ZT_e value is enhanced for both the nanowires. Our study stimulates both nanowire synthetization feasibility and thermoelectric applications for the conversion of waste heat into electricity.