Enhancing the thermoelectric performance of n-type Bi2Te2.7Se0.3 through the incorporation of Ag9AlSe6 inclusions

Bi2Te2.7Se0.3 (BTS) is the best commercial n-type thermoelectric alloy at near room temperature. However, as compared to its p-type counterpart, its figure of merit (ZT) and energy conversion efficiency are relatively low. Thus, the improvement of ZT for n-type BTS is imperative. Here, we show that the incorporation of the Ag9AlSe6 phase into BTS can remarkably reduce lattice thermal conductivity, due to the intensified phonon scattering from Ag9AlSe6 nanoparticles and interfaces. Meanwhile, the Seebeck coefficient is enhanced due to the decreased carrier concentration. The suppressed thermal conductivity leads to ZT(max) = similar to 1.2 at 423 K for the BTS-0.35 vol% Ag9AlSe6 sample, a similar to 38% increase compared to that for pristine BTS. Consequently, a high average ZT(ave) similar to 1.1 (300 K-473 K) is reached, indicating that the incorporation of the Ag9AlSe6 nanophase is an effective way to improve the thermoelectric performance of BTS.