Enhanced thermoelectric performance of Bi-Sb-Te/Sb <inf>2</inf> O <inf>3</inf> nanocomposites by energy filtering effect

Abstract

Engineering of thermoelectric materials through hybridization with nanoparticles has been proved effective to boost their thermoelectric efficiency by providing the means to decouple thermal and electrical transport phenomena. Here, we report the synthesis of p-type Bi0.5Sb1.5Te3/X wt% Sb2O3 (X = 0, 1, 2, 4, 6) nanocomposites, in which the Sb2O3 nanoparticles are dispersed mainly at the grain boundaries of the Bi0.5Sb1.5Te3 matrix. It is shown that incorporation of up to 4 wt% Sb2O3 into the matrix results in simultaneous enhancement of the Seebeck coefficient (by filtering of low energy charge carriers) and decline of thermal conductivity (mainly by charge carrier scattering at the interfaces), both of which contribute to improving the thermoelectric figure of merit to a maximum of 1.51 at 350 K. Moreover, the nanocomposites with 2, 4, and 6 wt% Sb2O3 demonstrate ZT > 1.0 up to 450 K, making them commercially appealing for thermoelectric applications in a wide temperature range. Furthermore, it is shown that Bi0.5Sb1.5Te3/4 wt% Sb2O3 samples exhibit excellent thermal and chemical stability in ambient atmosphere and 300–475 K temperature range over a 24 month period.