Enhanced thermoelectric performance of 3D-printed Bi2Te3-based materials via adding Te/Se

Bi 2 Te 3 -based materials were prepared by direct ink writing (DIW) 3D printing and their microstructure and thermoelectric properties were investigated with an emphasis on the effect of the content of DMF and Te/Se addition. As the mass ratio of DMF in the composition increased from 6.5% to 8.0% (in mass), the electrical conductivity deteriorated because of the corresponding increased porosity and organic remains in the samples. However, the volatilization of DMF would reduce the fluidity of the slurry. Thus, thermoelectric slurry with 7.0% DMF is the most suitable mass ratio for 3D printing. Additionally, adding Te in the p-type Bi 0.4 Sb 1.6 Te 3 and adding Se in the n-type Bi 2 Te 2.6 Se 0.4 have significantly improved their electrical conductivity due to the increased carrier concentration and mobility. Combining with the moderate Seebeck coefficient (∼200 μV/K), high power factors with ∼802 μW·m −1 ·K −2 and 1266 μW·m −1 ·K −2 were obtained for the n-type Bi 2 Te 2.6 Se 0.4 +10%Se and p-type Bi 0.4 Sb 1.6 Te 3 +7%Te, respectively, which result in the final relatively high zT values of 0.68 at 573 K and 0.56 at 330 K for n-type and p-type 3D-printed samples.