Composition-dependent thermoelectric properties of PbTe doped with Bi2Te3

The composition-dependent thermoelectric properties of PbTe doped with Bi2Te3 have been studied at room-temperature. The electrical resistivity and the Seebeck coefficient in absolute value decrease with an increase of Bi2Te3. A sharp maximum in the Seebeck coefficient at 0.3 mol% Bi2Te3 indicates that an electronic topological transition is occurred in PbTe alloyed with Bi2Te3. The total thermal conductivity nearly keeps constant and the parts of lattice, which are much lower than those doped with PbI2 prepared by hot-pressing, linearly decrease with increasing Bi2Te3. The figure of merit shows a maximum value of 7.63 × 10−4 K−1, which is several times higher than that of PbTe containing other dopants. The high thermoelectric performance is explained by electronic topological transition induced by alloying.