Simultaneously optimized thermoelectric performance of n-type Cu2Se alloyed Bi2Te3

To achieve the optimized performance and the widespread application of thermoelectric materials , it is crucial to decouple the highly interrelated thermoelectric parameters of materials. In this study, we illustrate that phonon and carrier transport properties of n-type Bi 2 Te 3 -based composites can be simultaneously optimized through alloying Cu 2 Se. Owing to the chemical reactions between the Bi 2 Te 3 matrix and the Cu 2 Se additives during the sample preparation, the carrier concentration and density-of-states effective mass can be tuned to optimize the carrier transport properties, while the lattice thermal conductivity can be reduced by introducing hierarchical structures including point defects , Cu 7 Te 5 inclusions, phase boundaries and localized Te-deficient regions. As a result, an enhanced thermoelectric performance is achieved compared with pristine Bi 2 Te 3 . Our study indicates the alloying Cu 2 Se can synergistically control the thermoelectric properties of Bi 2 Te 3 .