Enhanced performances of melt spun Bi2(Te,Se)3 for n-type thermoelectric legs

In this article, a rapid and cost-effective melt spinning (MS) subsequently combined with a spark plasma sintering (SPS) process was utilized to prepared n-type Bi2(Te1−xSex)3 (x = 0.0–1.0) solid solutions from high purity single elemental chunks. The substitution of tellurium by selenium has significant impacts on the electrical and thermal transport properties of the Bi2(SexTe1−x)3 compounds in a manner which can be well understood using a valence bond rule and the corresponding change in band gap. Furthermore, the selenium substitution effectively adjusts the carrier density allowing an optimum value of ∼5 × 10−19 cm−3. As a result, a maximum ZT of 1.05 at 420 K was achieved for the Bi2(Se0.2Te0.8)3 sample which also shows an improved average ZT of ∼0.97 in the entire measurement temperature range. By adopting the same p-type legs, the module fabricated by the MS-SPS Bi2(Se0.2Te0.8)3 material which acts as n-type legs shows ∼10% enhancement in thermoelectric conversion efficiency compared with the module fabricated by n-type zone melted ingots.