(AgSbTe2)1-x(Bi2Te3)x-based thermoelectric device for low-grade heat recovery

Abstract

Near room-temperature thermoelectric materials have promising applications for recovering low-grade waste heat, but high-performance p-type thermoelectric candidates are quite limited if compared with n-type ones. It is thus important to design new p-type materials with superior thermoelectric performance. AgSbTe₂ has received plenty of attention as a promising p-type material candidate due to its intrinsically low thermal conductivity, which is further decreased by introducing vacancies and substitutional point defects by alloying with Bi₂Te₃ in this work. With the additional help of Cd substitution at the Sb site, the optimized carrier concentration leads to a peak zT value of 0.93 at 450 K for (AgSb_0.98Cd_0.02Te₂)_0.9(Bi₂Te₃)_0.1, and the corresponding single-leg device achieves a conversion efficiency of ∼4.2 % at a temperature gradient ΔT of ∼162 K. By further pairing with an n-type Ag₂Se leg, a conversion efficiency of ∼1.8 % is realized at a ΔT of ∼93 K for the obtained module, suggesting its potential applications in the low-grade heat recovery.