The enhancement of thermoelectric performance of p-type Li doped Mg2Ge0.4Sn0.6 by Si addition

Abstract Mg 2 (Ge, Sn) solid solutions are eco-friendly thermoelectric materials in moderate temperature (500–800 K) range. However, p-type Mg 2 (Ge, Sn) solid solutions show poor thermoelectric performance compared to the n-type counterpart. In this work, the filtering of low energy holes and the blocking of thermal excited electrons in Mg 1.92 Li 0.08 Ge 0.4 Sn 0.6 by Si addition are demonstrated, which optimize the power factor by interface barrier and reduce the lattice thermal conductivity by nanoscale composition fluctuation. Finally, the power factor of ~1.85 × 10 −3 Wm −1  K −2 and the dimensionless figure of merit ZT ~0.75 are achieved in Li doped Mg 2 Ge 0.4 Sn 0.6 with Si addition at 723 K.