Effect of Cu doping on microstructure and thermoelectric properties of Bi2Te2.85Se0.15 bulk materials

Cu was incorporated into Bi₂Te_2.85Se_0.15 compound as a dopant, and the microstructure and thermoelectric properties of sintered Cu_xBi₂Te_2.85Se_0.15 samples have been investigated. The Cu atoms intercalated into interstitial sites along the c-axis, which caused an increase in lattice constant c. The accommodation of Cu in Bi₂Te_2.85Se_0.15 reached saturation at x = 0.05 and the excessive Cu formed a copper telluride compound. The interstitial Cu resulted in decreases in carrier concentration and phonon thermal conductivity as well as an increase in carrier mobility. A maximum ZT value was obtained at x = 0.05, which was enhanced for about 4 times compared to Cu-free sample.