Enhancement in the figure of merit of p-type Bi100−xSbx alloys through multiple valence-band doping

N-type Bi100−xSbx alloys have the highest thermoelectric figure of merit (zT) of all materials below 200 K; here, we investigate how filling multiple valence band pockets at the T and Η-points of the Brillouin zone produces high zT’s in p-type Sn-doped material. This approach, theoretically predicted to potentially give zT > 1 in Bi, was used in PbTe. We report thermopower, electrical and thermal conductivity (2 to 400 K) measurements 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.