Fabrication of Silver-Doped (Bi,Sb)2Te3 Thermoelectric Film Prepared from Ag Nanoparticles/Bi-Sb-Te Pastes.

ABSTRACT

Film-type thermoelectric generator (TEG) utilizing Bi-Te based paste has been highly considered as advanced power sources for the wearable electronic devices due to its light, thin and flexible characteristics when producing electricity from certain thermal resources such as human body heat. However, the application of the film-typed TEG has been often limited due to its low TE conversion efficiency caused by low electrical conductivity resulting from severe porosity. Thus, it is crucial to increase electrical properties via densification of the TE film. Here, we synthesized silver nanoparticle (AgNP)-dispersed (Bi,Sb)2Te3 (BSbT) powders to fabricate AgNP-BSbT pastes by adding organic binder. The synthesized AgNP-BSbT pastes were printed through a hand-painting process and were consolidated into Ag-doped BSbT (Ag-BSbT) thick film with a few hundreds µm with controlled 2-step heat treatment. The microstructures of Ag-BSbT films show abnormally elongated grains but also the amount of porosities in the film significantly decreased by addition of AgNP. As a result, it is confirmed that the 0.072 at% Ag-BSbT thick film exhibits power factor of 2.93 × 10-3 W/mK² at room temperature, which is comparable to that of practically utilized bulk materials. It is elucidated that the increase in power factor originates from the modulation between electrical conductivity and Seebeck coefficients due to increased hole carrier density at room temperature.