Research progress on the flexible thin-film thermoelectric devices

The recent research progress of flexible thin-film thermoelectric devices is presented from the following aspects: the choice of the flexible substrates, the types of thermoelectric materials, the deposition process of thermoelectric thin films, the introduction of buffer layer, and the design of devices. At the same time, the major aspects in selection of thermoelectric materials and deposition process of thin films have been summarized. By comparison among the performances of reported thermoelectric devices, the flexible thin-film thermoelectric devices with alloy of (Bi,Sb)₂Te₃ show the best performance and the output voltage of single thermocouple can reach 0.1-0.3 mV with the temperature difference of 1 K, which nearly equals to the Seebeck coefficient of thermoelectric materials on the condition of sufficiently low internal resistance. Increasing the thickness of thermoelectric thin film can reduce the internal resistance of thermocouple effectively, and therefore improve the output voltage of flexible thin-film thermoelectric devices.