BandGap Size or Band Shape? The Real Determinant of Excellent Thermoelectric Variables

The interest in thermoelectric materials (TMs) have persisted for two obvious reasons. The first is that a large part of almost all energy consumption process is lost in the form of wasted heat and thermoelectric materials are good at converting heat directly to electricity. Secondly, TMs can convert heat to electricity without harmful bye-products. TMs with high efficiency is somewhat difficult to achieve because of the interplay of factors around materials electronic structure. While a material band shape is believed to offer some definite impact on thermoelectric variables, the bandgap size role is not clear. Motivated by these observations, two compounds (BaSrSi and IrBiZr) have been evaluated for optimum hermoelectric application. Despite their comparable bandgap size, the peculiar band shape of IrBiZr gave it an overall superior performance over BaSiSr. To our understanding, these compounds are proposed and investigated for the first time. The results are profound to indicate lesser role for bandgap size in the design and optimization of novel thermoelectric materials.