Thermoelectric properties of In-Hg co-doping in SnTe: Energy band engineering

Abstract

Synergistic effect of band convergence and resonant level could be manipulated in SnTe by co-doping In and Hg, leading to a potential thermoelectric performance enhancement in a much wider temperature range. In this work we carefully investigated thermoelectric properties of the In-Hg co-doped SnTe, synthesized by a hot pressing method. With this co-doping the Seebeck coefficients of the co-doped samples were greatly improved (over 50 μVK−1) at the room temperature. Although power factors of the In-Hg co-doped SnTe were also able to be optimized, the peak ZT (0.9 at 850 K in Sn0.98Bi0.02Te-1%HgInTe2), however, is not high enough when comparing to other co-doped SnTe systems. This may be caused by the relatively high lattice thermal conductivity. An apparent competition between band convergence doping and resonant level doping was observed in our experiment. The results suggest that band engineering via co-doping should be further understood in order to optimize the thermoelectric properties inside the material system.