ICT2014 Abstracts

Impedance spectroscopy is one of the most helpful techniques for the characterization of a wide range of devices (solar cells, supercapacitors, fuel cells, etc.). However, it is not extensively used in the thermoelectric field and most of existing work is mainly focused on its application to determine the figure of merit zT.

This study analyses the use of ac impedance spectroscopy as a characterization tool applied to bulk thermoelectric elements. First, we present the theoretical background required for the interpretation of the measurements based on solving the heat balance equation in the frequency domain under adiabatic conditions and Peltier mode operation. Secondly, we validate the theoretical models by fitting experimental results obtained from single thermoelectric elements. It is shown that all the relevant thermoelectric parameters and thermal properties can be potentially extracted at a given temperature from the impedance spectra, i. e., the Seebeck coefficient, electrical resistivity, thermal conductivity, figure of merit (zT), specific heat, and thermal diffusivity. The simple nature of the measurements in conjunction with the advantage of obtaining all the important thermoelectric parameters opens up the possibility of establishing impedance spectroscopy as a very useful characterization method for the thermoelectric field.