Influence of gallium doping on structural and thermoelectric properties of bismuth telluride

Abstract

Pure and gallium-doped bismuth telluride (Bi2Te3) nanostructures were synthesized by solvothermal method at 200 °C for 24 h. The undoped Bi2Te3 nanostructures show flower-like morphology, on gallium-doping, the Bi2Te3 nanostructures show flake-like morphology. The thermoelectric measurements of nanostructured bulk sample show an enhancement in power factor in gallium-doped Bi2Te3 from around 60 μWm-1K−2 at 150 °C for undoped Bi2Te3 to around 960 μWm-1K−2 at 150 °C for 0.2 mmol gallium-doped Bi2Te3 and with the increase in gallium-doping to 0.3 mmol, the power factor was found to decrease to around 400 μWm-1K−2 at 150 °C. The figure of merit (ZT) value was found to be around 0.08 at 50 °C for undoped Bi2Te3 and for 0.2 mmol gallium-doped Bi2Te3 the ZT values was found around 1.1 at 50 °C. Further, increase in the ZT value shows a decreasing trend and for 0.3 mmol gallium-doped Bi2Te3ZT value was found to be around 0.8 at 50 °C.