Attaining High Figure of Merit in the N-Type Bi2Te2.7Se0.3-Ag2Te Composite System via Comprehensive Regulation of Its Thermoelectric Properties

n-Type Bi2Te2.7Se0.3 (BTS) isthe state-of-the-art thermoelectric material near room temperature.However, the figure of merit ZT of commercial BTSingots is still limited and further improvement is imperative fortheir wide applications. Here, the results show that through dispersionof the Ag2Te nanophase in BTS, one can not only elevateits power factor (PF) by as high as 14% (at 300 K) but also reduceits thermal conductivity & kappa;(tot) to as small as & SIM;29%(at 300 K). Experimental evidences show that the improved PF comesfrom both increased electron mobility via inhibited Te vacancies andenhanced thermopower due to energy filtering effect, while the reductionof & kappa;(tot) originates from the drop of both electronicthermal conductivity largely owing to the reduced number of vacancy V Te & BULL;& BULL; and intensified phonon scattering chiefly from the dispersed Ag2Te nanophase. Consequently, the largest ZT (max) = 1.31 (at 350 K) and average ZT (ave) = 1.16 (300-500 K) are achieved for the Bi2Te2.7Se0.3-0.3 wt % Ag(2)Tecomposite sample, leading to a projected conversion efficiency & eta; = 8.3% (300-500 K). The present results demonstratethat incorporation of nanophase Ag2Te is an effective approachto boosting the thermoelectric performance of BTS.

Automated summary

By dispersing Ag2Te nanophase in BTS, the power factor (PF) is elevated by 14% and the thermal conductivity is reduced by 29%. The incorporation of nanophase Ag2Te leads to a maximum ZT of 1.31 and an average ZT of 1.16, demonstrating the effectiveness of this approach in boosting the thermoelectric performance of BTS.