Review: The effect of different nanofiller materials on the thermoelectric behavior of bismuth telluride

This review paper summarizes and discusses the effect of nanosized fillers on bismuth telluride nanocomposites for thermoelectric applications. Classified into various dimensions based on electron confinement in space, the nanofiller effect on the figure-of-merit value is studied. By combining experimental data with theoretical models, the mechanisms for enhancing the thermoelectric properties were proposed. The outcomes of this review paper suggest that doped bismuth telluride composites (doped with selenium for n-type or antinomy for p-type) offer better thermoelectric properties compared to undoped composites. Moreover, improvements in undoped bismuth telluride composites are exclusive for the n-type only. The figure-of-merit value for bismuth telluride composites is less than two, where the 2D nanofillers show optimum ZT improvements. Nevertheless, the inconsistency of reported data in the thermoelectric area is a problem that must be addressed to have more control over the precision of the reported results for a better understanding of the concepts in this field.