Enhancement in the Figure of Merit of p-type BiSb alloys through multiple valence-band doping

TL;DR

This study enhances the thermoelectric figure of merit in p-type BiSb alloys by multiple valence-band doping, achieving a 60% improvement in zT through experimental analysis of various compositions.

Contribution

It demonstrates the successful application of multiple valence-band doping in p-type BiSb alloys to significantly improve thermoelectric performance.

Findings

zT improved by 60% to 0.13

Effective doping increases thermopower and reduces thermal conductivity

High Sb concentrations extend the temperature range of high zT

Abstract

N-type Bi100-xSbx alloys have the highest thermoelectric figure of merit (zT) of all materials below 200K; here we investigate how filling multiple valence band pockets at T and H-points of the Brillouin zone produces high zT in p-type Sn-doped material. This approach, theoretically predicted to potentially give zT>1 in Bi, was used successfully in PbTe. We report thermopower, electrical and thermal conductivity (2 to 400K) of single crystals with 12<x<37 and polycrystals (x=50-90), higher Sb concentrations than previous studies. We obtain a 60% improvement in zT to 0.13.