Progress in measurement of thermoelectric properties of micro/nano thermoelectric materials: A critical review

Thermoelectric materials have attracted extensive attentions due to their extensive applications in thermoelectric refrigeration, waste heat recovery, aerospace and other fields. The effective improvement of thermoelectric properties of thermoelectric materials is of far-reaching significance to broaden their applications. One of the important methods is to improve thermoelectric performance by low dimension and nano-crystallization. Even though small-scale measurement is difficult to conduct, it is very important to accurately measure the thermoelectric properties for micro/nano thermoelectric materials. At present, different methods are used to measure the thermal and electrical parameters. However, using different methods to measure thermoelectric parameters will make measurement error transmission, resulting in large final ZT error. Moreover, transferring samples multiple times during separate measurements for different physical properties can result in impaired surface appearance of microscale samples, thus affecting their intrinsic physical properties. In addition, due to the remarkable difference between the individual samples, it is better to measure all the properties from the same individual sample. Therefore, it is necessary to study the in-suit integrated measurement method. This review summarizes the measurement methods of thermoelectric properties of micro/nano thermoelectric materials, including thermal conductivity, Seebeck coefficient and electrical conductivity. The existing integrated measurement methods of thermoelectric properties for part of micro/nano thermoelectric materials are also summarized. Finally, the difficulties of the integrated measurement methods are proposed and some strategies of the integrated measurement methods which are suitable for one-dimensional nanotubes and two-dimensional films are also prospected.