Uplimit (ZT)max and effective merit parameter B* of thermoelectric semiconductors

Abstract

Thermoelectric materials directly convert thermal energy and electrical power, attracting wide attention. New materials and new strategies to pursue a high ZT value mark the progress of thermoelectric materials. However, the critical factors relative to a given material's uplimit (ZT)max in the dual-parameter space of temperature carrier concentration are still an open question. In this work, we theoretically show that (ZT)max has a proximately linear relationship with B* that connects the weighted mobility, lattice thermal conductivity, and the bandgap in a single parameter. We also provide insight discussion for achieving a high B* by pursuing high U*, large Eg, and low κlat, or breaking the connections among κlat versus U*, Eg versus κlat, U* versus Eg, suggesting that B* is a good primary effective merit parameter for quick screening new thermoelectric materials.