Enhanced Thermoelectric Performance of Bulk Bismuth Selenide: Synergistic Effect of Indium and Antimony Co-doping

The thermoelectric (TE) performance of pristine Bi2Se3 is inferior to that of Bi2Te3. Therefore, the study on Bi2Se3 has faced a decline. The lower performance is due to the low power factor and high thermal conductivity. In recent years, single aliovalent doping has been adopted to improve the TE performance of Bi2Se3. Here, we adopt an isovalent co-doping approach using indium and antimony to create a manifold enhancement in the TE performance of Bi2Se3 via the creation of neutral impurities and deep defect states (DDSs). A high figure of merit (ZT = 0.47) is obtained at 473 K for a doping concentration of 0.1 at. %. The TE performance obtained for Bi2-xInxSb2x/3Se(3), x = 0.1 at. %, is comparable to that obtained in several reports for pristine Bi2Te3. Our density functional theory calculation reveals an underlying DDS located at similar to 15 eV below the Fermi level. This leads to enhanced electronic properties via density of states optimization induced by the co-doping. The isovalent doping is expected to create neutral impurities, which causes less scattering to conduction electrons while absorbing phonon vibration, thus improving the TE performance.