Enhancing the thermoelectric performance of Sb2Si2Te6 by germanium doping

Abstract

Thermoelectric materials, which can directly convert thermal energy into electricity, play an important role in waste heat recovery. Sb₂Si₂Te₆ is a promising medium-temperature thermoelectric material for power generation. However, its application is restricted by the relatively low power factor (PF) and the decompostion at high temperature. Herein, we successfully improved the power factor of Sb₂Si₂Te₆ by doping with germanium (Ge). Benefiting from the optimized carrier concentration, the power factor of Sb₂Si_1−xGe_xTe₆ remains higher than 1100 μW m⁻¹ K⁻² from 473 K to 773 K and the highest zT value reaches 1.0 at 773 K. Furthermore, the power generation performance of a single-pair thermoelectric module, consisting of Sb₂Si_1.94Ge_0.06Te₆ and Mg_3.2Sb_1.5Bi_0.49Te_0.01, is evaluated by three-dimensional numerical simulation. The simulated conversion efficiency is as high as 13% at a temperature difference of 500 K, and the power density can reach up to 3 W cm⁻². Our results demonstrate that Ge doping can effectively modify the thermoelectric properties of Sb₂Si₂Te₆ and improve its power generation performance, paving the way for realistic applications in the medium-temperature region.