Suppressed intrinsic excitation and enhanced thermoelectric performance in AgxBi0.5Sb1.5−xTe3

Abstract

Bi₂Te₃-based alloys are the most well-known thermoelectric materials for room-temperature applications. However, the maximum ZT values of Bi₂Te₃-based materials are usually achieved near room temperature. The ZT values dramatically drop above 400 K because of the intrinsic thermal excitation in Bi₂Te₃-based materials, which seriously restricts their applications as thermoelectric power generators. In this study, by doping a tiny amount of Ag into Bi_0.5Sb_1.5Te₃, we successfully suppressed the intrinsic excitation in p-type Bi₂Te₃-based materials and shifted the ZT peak temperature to high temperatures. Eventually, due to the enhanced power factor and greatly depressed bipolar thermal conductivity at high temperature, a maximum ZT of 1.25 at 400 K was obtained in Ag_0.002Bi_0.5Sb_1.498Te₃, and an average ZT value of approximately 1.03 was achieved between 300 and 600 K. The theoretical energy conversion efficiency of the TE module fabricated with Ag_0.002Bi_0.5Sb_1.498Te₃ achieves a maximum value of 11.0% when ΔT = 300 K, which makes p-type Bi₂Te₃-based devices attractive for applications in TE power generation.