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

Abstract

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 TiSi 2 -type RuGa 2 and the lead chalcogenides PbTe and PbSe.

Reinvestigation of the Thermoelectric Properties of Fe‐Substituted Icosahedral Al–Pd–Re Quasicrystals

“…They form a deep pseudogap near the Fermi level originating from icosahedral symmetry and covalent bonding nature. [6,7] One feature of icosahedral QCs is a glass-like, low κ total at room temperature owing to their complex crystal structures with icosahedral symmetry. Extensive experimental [8] and theoretical [9] studies on QCs and related ACs have been performed to understand the physics behind materials and enhance their thermoelectric performance.…”

Negative‐to‐Positive Thermal Conductivity Temperature Coefficient Transition Induced by Dynamic Fluctuations of the Alkyl Chains in the Layered Complex (C4H9NH3)2CuCl4

“…Aperiodic lattice structures represent a promising technology to realize the seemingly contradictory properties of sufficient electric conductivities and low heat transportation in thermoelectric materials . Quasicrystals are also considered to be promising candidates for such materials because of the large gap in their phonon band structures and their low thermal conductivities …”

“…[15,16] Quasicrystals are also considered to be promising candidates for such materials because of the large gap in their phonon band structures and their low thermal conductivities. [17] Incommensurate crystal structures are also found in the family of organic-inorganic 2D layered compounds with the structure (C n H 2n + 1 NH 3 ) 2 MX 4 (CnMX4,M 2 + = Cu 2 + ,M n 2 + ,Z n 2 + , etc.,X À = Cl À ,B r À ). [18][19][20][21][22][23][24] These compounds show sequential temperature-dependent structural phase transitions, with some phases exhibitingi ncommensurate structures.…”