Pressure-induced semimetal-semiconductor transition and enhancement of thermoelectric performance in α -MgAgSb

Comparable to bismuth telluride, α-MgAgSb-based materials (α-MAS) have been investigated recently as promising candidates for room-temperature thermoelectric energy harvesting and thus various efforts have been devoted to the enhancement of their thermoelectric performance. By utilizing first-principles density functional calculations and Boltzmann transport theory, we report that the thermoelectric properties of α-MAS can be dramatically improved with the application of hydrostatic pressure. This is attributed to a pressure-induced semimetal to semiconductor transition in α-MAS. With the benefit of this pressure-tunable behaviour, the Seebeck coefficient of α-MAS can be manipulated flexibly. Furthermore, we found that, through the combination of applying pressure and p-type doping, the optimal thermoelectric power factor and figure of merit of α-MAS can be enhanced remarkably by 110% at 550 K compared with the intrinsic case. Our results provide an interesting insight and a feasible guideline for the improvement of the thermoelectric properties of α-MAS related materials.