Carrier concentration and orientation optimization for high performance (Sb,Bi)2Te3 thermoelectric films via magnetron co-sputtering

High performance flexible thermoelectric thin films are desired for power generation of flexible thermoelectric device. Thermoelectric performance of (Sb,Bi)2Te3 films are determined by the Te content in the matrix as anti-site defect dominates the carrier concentration. By controlling the Te target co-sputtering power, annealing temperature and time, not only the film in-plane orientation is enhanced, the carrier concentration is also effectively controlled in this work. Through a systematically investigation of Te content dependence of the thermoelectric performance, the carrier concentration and orientation is optimized through tuning Te content, and a high power factor of ∼32 μW/cm-K2 for Sb2Te3 film, ∼36 μW/cm-K2 for Bi0.5Sb1.5Te3 film is realized in in-plane orientation. Besides, The thermal conductivity along in-plane direction is determined by photon-electro-thermal (TPET) technique, and the final zT values are ∼0.49 for Sb2Te3, and ∼0.58 for Bi0.5Sb1.5Te3 films at room temperature, respectively.