Ag-doping induced enhancement in power factor of flexible n-type Bi2Te2.7Se0.3 thin films

Bi2Te3-based materials are the mostly utilized commercial thermoelectric material near room temperature, yet their performance and flexibility require further enhancement. Herein, n-type Bi2Te2.7Se0.3 thin films with trace Ag-doping were fabricated on flexible polyimide substrates via magnetron cosputtering. The Ag-doping plays a multifunctional role in tuning the charge carriers, probably acting as interstitial donors to supply electrons while forming Ag—Te(Se) bonds to suppress intrinsic vacancies as well which provides the possibility to achieve the synergistical optimization in electrical transport by altering the Ag-doping level. As a result, the Bi2Te2.7Se0.3 film with Ag cosputtering of 60 s reveals a maximum power factor of 613.5 μW m−1 K−2 at 500 K, representing a 45.4% increment over the Ag-free film.