Improvement of the Thermoelectric Performance of Pseudogap and Narrow-Gap Compounds via Theoretical Calculations

This review briefly discusses the relationship between the crystal structures, electronic structures, and thermoelectric properties of materials such as pseudogap quasicrystals and related approximant crystals, narrow-gap binary intermetallic compounds, and lead chalcogenides. The approach used is to identify the materials' intrinsic physical properties from experimental data and establish a route for tuning their properties based on theoretical models and first-principles calculations. A possible route for improving thermoelectric performance is to use a band engineering approach, such as band convergence and introducing impurity states near the valence and conduction band edges. This approach was successfully applied to TiSi2-type RuGa2 and the lead chalcogenides PbTe and PbSe.