Thermoelectric properties of Bi2SexTe3−x prepared by Bridgman method

Bi2SexTe3−x crystals with various x values were grown by Bridgman method. The electrical conductivity, σ, was found to decrease with increasing Se content. The highest σ of 1.6 × 105 S m−1 at room temperature was reached at x = 0.12 with a growth rate of 0.8 mm h−1. The Seebeck coefficient, S, was less dependent on Se content, all with positive values showing p-type characteristics, and the highest S was measured to be 240 μV K−1 at x = 0.24. The lowest thermal conductivity, κ, was 0.7 W m−1 K−1 at x = 0.36. The electronic part of κ, κel, showed a decrease with increasing Se content, which implies that the hole concentration as the main carriers was reduced by the addition of Se. The highest dimensionless figure of merit, ZT, at room temperature was 1.2 at x = 0.36, which is attributed to the combination of a rather high electrical conductivity and Seebeck coefficient and low thermal conductivity.

► Bi2SexTe3−x with various Se concentrations grown by Bridgman method was prepared. ► The electrical conductivity was found to decrease with increasing Se content. ► The Seebeck coefficient was not influenced by the substitution of Te with Se. ► The electronic thermal conductivity exhibited a decrease with increasing Se. ► The highest of dimensionless figure of merit (ZT) was measure to be 1.2.