Effects of bismuth doping on the thermoelectric properties of Cu3SbSe4 at moderate temperatures

The thermoelectric properties of the bismuth doped compounds Cu3Sb1−xBixSe4, prepared by melting method and spark plasma sintering (SPS) technique, were investigated in the temperature range from 300 K to 600 K. The results indicate that the electrical resistivity of the Bi-doped compounds decreased as compare to Cu3SbSe4 due to the increase in the hole concentration; also thermal conductivity lowered after doping, which can be attributed to the strong phonons scattering by atom mass fluctuations. Moreover, it is found that the state of density effective mass m* increases for the doped compounds, which could be responsible for the enhanced thermopower at T > ∼400 K. The largest ZTmax = 0.7 is achieved at 600 K for Cu3Sb0.98Se0.02, which is about 3.3 times larger than that of the un-doped compounds.

► Bi was successfully substituted for Sb in Cu3SbSe4.
► ZT for doped compounds was greater than that of un-doped Cu3SbSe4.
► In particular, ZT of Cu3Sb0.98Bi0.02Se4 reached a value of 0.7.
► Our results indicate Bi doping is an efficient way in improving TE properties.