Enhanced power factor and figure of merit through magnesium doping in Sb2Si2Te6

We report here a high thermoelectric performance in magnesium (Mg) doped Sb 2 Si 2 Te 6 . The substitution of Mg 2+ for Sb 3+ in Sb 2 Si 2 Te 6 induces a synergetic effect on electrical transport performance, exciting multi-band carrier transport behavior, enhancing carrier concentration, and increasing the density of states effective mass. Such effects lead to the highest power factor of 10.95 μW cm −1 K −2 at 824 K for the Sb 1.99 Mg 0.01 Si 2 Te 6 , representing a ∼22 % increase compared to pristine Sb 2 Si 2 Te 6 . In addition, Mg doping induces Mg Sb − ${\text{Mg}}_{\text{Sb}}^{-}$ point defects phonon scattering, resulting in a low thermal conductivity of ∼0.52 W m −1 K −1 at 824 K. The simultaneous optimization of the power factor and thermal conductivity in Sb 1.99 Mg 0.01 Si 2 Te 6 leads to a peak ZT of ∼1.15 at 824 K and an average ZT of ∼0.68 (400−824 K), showing its potential for power generator at medium temperature.