Effects of Nb doping on the thermoelectric performance of CuI doped n-type Bi2Te3

Abstract The thermoelectric properties of Nb-doped (CuI)0.003Bi2-xNbxTe2.7Se0.3 compounds (x = 0, 0.005, 0.01 and 0.03), were investigated at temperatures ranging from 300 to 600 K. Among the compounds studied, the lightly substituted (CuI)0.003Bi1.995Nb0.005Te2.7Se0.3 compound exhibited the best thermoelectric performance due to the improvement in its electrical conductivity and its relatively unchanged Seebeck coefficient due to Nb doping. Its figure of merit, ZT, was greater than the undoped (CuI)0.003Bi2Te2.7Se0.3 compound for the temperature range investigated. In particular, the ZT of (CuI)0.003Bi1.995Nb0.005Te2.7Se0.3 reached a value of 0.65 at 448 K in this study.