Energy Filtering of Charge Carriers: Current Trends, Challenges, and Prospects for Thermoelectric Materials

TLDR

Thermoelectric materials are being intensively studied to convert waste heat to electricity, and energy filtering is a strategy to boost thermopower, though practical constraints limit its effectiveness. The paper reviews theoretical concepts, experimental evidence, and the authors’ perspective on energy filtering for thermoelectric materials. Based on literature data, energy filtering modifies the dependence of thermopower and conductivity on carrier concentration. Studies show that the magnitude of energy filtering varies across materials, and overcoming its constraints could improve power factor and figure of merit.

Abstract

Abstract Exhaustive attempts are made in recent decades to improve the performance of thermoelectric materials that are utilized for waste heat‐to‐electricity conversion. Energy filtering of charge carriers is directed toward enhancing the material thermopower. This paper focuses on the theoretical concepts, experimental evidence, and the authors' view of energy filtering in the context of thermoelectric materials. Recent studies suggest that not all materials experience this effect with the same intensity. Although this effect theoretically demonstrates improvement of the thermopower, applying it poses certain constraints, which demands further research. Predicated on data documented in literature, the unusual dependence of the thermopower and conductivity upon charge carrier concentrations can be altered through the energy filtering approach. Upon surmounting the physical constraints discussed in this article, thermoelectric materials research may gain a new direction to enhance the power factor and thermoelectric figure of merit.