Abstract Scope |
For decades n-type Bi2Te3-xSex compounds have remained the mainstream n-type thermoelectric material for solid-state cooling and power generation near room temperature. However, the performance of n-type Bi2Te3-xSex is inferior to that of p-type Bi2-xSbxTe3 near room temperature, restricting the device efficiency. In this work, we developed high performance n-type Bi2-xSbxTe3, a composition long thought to only make good p-type thermoelectrics, owing to a synergy of the following: (i) The donor-like effect is compensated by the antisite defects regulated by Sb alloying; (ii) the conduction band degeneracy increases from 2 for Bi2Te3 and Bi2Te3-xSex to 6 for Bi2-xSbxTe3, favoring high Seebeck coefficients; and (iii) larger mass fluctuation but smaller electronegativity difference and smaller atomic radius difference between Bi and Sb than those between Se and Te effectively suppress the lattice thermal conductivity and retains decent carrier mobility. A state-of-the-art zT of 1.0 near room temperature was attained in hot deformed Bi1.5Sb0.5Te3. |