Improved thermoelectric performance in wide temperature range of flexible moderately Ag-doped Bi0.5Sb1.5Te3 films

Motivated by previous investigations on Ag-doped Bi0.5Sb1.5Te3 films deposited on various kinds of substrates, we introduced the Ag doping of moderate content into flexible Bi0.5Sb1.5Te3 films through magnetron co-sputtering. The Ag doping level was found to have significant influence on the film microstructure and orientation. The remarkedly increased carrier concentration suppresses the bipolar conduction, contributing to superior thermoelectric performance in a wide temperature range from 300 K to 580 K. As a result, the 3.5 % Ag-doped Bi0.5Sb1.5Te3 film reveals the highest PF value of 1373 mu Wm(-1) K-2 at 480 K, as well as the best average PF of 1290 mu Wm(-1) K-2 within 300-580 K, which are competitive among the flexible BiSbTe-based thin films.