Multi-layered-stack thermoelectric generators using p-type Sb2Te3 and n-type Bi2Te3 thin films by radio-frequency magnetron sputtering

To provide power to electronic sensors operating at low power, we prepared multi-layered-stack thermoelectric generators using radio-frequency (RF) magnetron sputtering. Prior to the preparation of thermoelectric generators, Sb2Te3 and Bi2Te3 thin films were deposited on glass substrates followed by carrying out thermal annealing at temperatures ranging from 200 to 400 °C in order to investigate and improve their thermoelectric properties. Both the films exhibited the maximum power factor values measured at room temperature, namely, 12.7 μW/(cm·K2) for Sb2Te3 and 10.2 μW/(cm·K2) for Bi2Te3, at an annealing temperature of 300 °C. Therefore, the films annealed at 300 °C are suitable for fabricating multi-layered-stack thermoelectric generators. To prepare thermoelectric generators, Sb2Te3 and Bi2Te3 thin films were deposited on the top and bottom sides of 0.3 mm-thick glass substrates, respectively. Eleven sample pieces were connected in series by spraying silver paste to obtain the multi-layered-stack thermoelectric generators. Generators with dimensions of 20 × 30 mm2 and a thickness of 7 mm were fabricated. The thermoelectric generators exhibited an open circuit voltage of 32 mV and maximum output power of 0.15 μW at a temperature difference (on both ends) of 28 K.