Improved thermoelectric performance of Se-doped n-type nanostructured Bi2Te3

Pure and Se-doped Bi₂Te₃ nanostructures are prepared by solvothermal method at 190 °C for 24 h. Rhombohedral crystal structures in both cases are confirmed by XRD. They possess nanoplate-like morphology. Carrier concentrations and carrier mobilities are measured using Hall effect measurement. The vibrational modes are obtained using Raman spectroscopy. The energy band gap of 1.58 eV is obtained for doped sample by Tauc plot. The prepared samples are porous as confirmed by FESEM and density measurement. Thermoelectric measurement proves that the power factor enhances from 0.65 to 0.89 mWm⁻¹ K⁻² at 385 K with Se doping of Bi₂Te₃. The total thermal conductivity (k) decreases from 0.39 to 0. W/mK at room temperature due to the formation of point defects and mass fluctuations between different atoms. As a result, figure of merit (ZT) for Bi₂Te₃ increases from 0.37 to 0.61 at 385 K with Se doping which is 64% higher than pure Bi₂Te₃.