Enhanced thermoelectric performance of p-type Bi₀₄Sb₁₆Te₃ by excess Te addition

Thermoelectric properties of p-type Bi_0.4Sb_1.6Te₃ polycrystalline bulks fabricated by spark plasma sintering from the ingots of stoichiometric Bi_0.4Sb_1.6Te₃ and 0.5–3 wt.% excess Te added compositions were investigated in an effort to demonstrate the feasibility of traditional melt-solidification combined with a pressure induced sintering process. We found that the electronic and thermal transport properties of p-type Bi_2-xSb_xTe₃ could be optimized by excess Te addition due to the suppression of uncontrollable formation of Te-vacancies during the fabrication process. Enhanced thermoelectric performance ZT of 1.1 at 300 K was obtained in 1, 2, and 3 wt.% excess Te added Bi_0.4Sb_1.6Te₃. High ZT and superior controllability of the thermoelectric transport parameters achieved in the present study enable the pressure induced sintering process to be utilized for commercial manufacturing process for solid state cooling and power generation modules.