Thermodynamic efficiency of mesoscopic thermoelectric generators with broken time-reversal symmetry: Insights from an ecological optimization

Abstract

We study the performance optimization for mesoscopic thermoelectric generators (MTGs) with broken time-reversal symmetry by using an ecological criterion, and some specific properties of the thermoelectric system are further revealed. We discuss the working regimes of time-reversal symmetric mesoscopic (macroscopic) thermoelectric generators, and find that a larger thermodynamic efficiency can be obtained only when the Wiedemann–Franz (WF) law is strongly violated. Furthermore, a definite dependence of the optimal bound efficiency (power) on the asymmetry parameter and the generalized thermoelectric figure of merit is analytically determined, and it is found that the usual value [Formula: see text] can be readily overcome. A larger efficiency can be obtained with the further enhancement of broken time-reversal symmetry, although the power output does not synchronize with efficiency. Interestingly, both the increase of the number [Formula: see text] of terminals and the external magnetic field open up the possibility to physically enhance the performance of thermoelectric generators, and the underlying physical origin of the improved energy conversion is also provided. The obtained results can contribute to a profound insight of thermodynamic performance for MTGs.