Tin Acceptor Doping Enhanced Thermoelectric Performance of n-Type Yb Single-Filled Skutterudites via Reduced Electronic Thermal Conductivity.

Although introducing more fillers in nanocages is beneficial to gain low lattice thermal conductivity within filling fraction limit, accompanying high electronic thermal conductivity usually results in an unsatisfactory figure of merit ZT in CoSb3. In this work, Sn is adopted to tailor the electronic transport behavior for a high-filled Yb0.3Co4Sb12 alloy through rapid melt spinning combined with hot-press sintering processes. In spite of the reduced electrical conductivity, the power factors are scarcely influenced due to improved Seebeck coefficients by the reduced carrier concentration and moderate ionized impurity scattering. However, the lower total thermal conductivity is synergistically tuned by the effective suppression of electronic thermal conductivity and the low lattice thermal conductivity. As a result, both the high maximum ZT value of 1.4 at 823 K and the average ZT value of ∼0.98 between 300 and 850 K can be achieved in the Yb0.3Co4Sb11.85Sn0.15 sample. This work illustrates a promising approach for improving thermoelectric properties by largely tuning the electronic thermal conductivity.