Effective mass model for thermoelectrics

Abstract

Thermoelectric materials require precise doping to adjust the Fermi level in order to fully realize their thermoelectric potential. The effective mass (EM) model is commonly used to predict the maximum thermoelectric figure-of-merit (zT) and optimal carrier concentration, but its application is limited by the need for numerical Fermi integral solutions and Hall effect measurements. Since the thermopower (magnitude of the Seebeck coefficient, |S|) is effectively a measure of the Fermi level, it can be used as a direct descriptor of doping level in heavily doped semiconductors such as good thermoelectric materials. Here, we present a simple method to analyze thermoelectric transport using only the typical thermoelectric measurements: Seebeck coefficient, electrical conductivity and thermal conductivity. This enables evaluation of weighted mobility, quality factor (B), theoretical maximum zT, optimal thermopower, identification of anomalous scattering behavior; as well as a full prediction of zT, as a function of |S| given by