Enhancing the thermoelectric power factor with highly mismatched isoelectronic doping

Area of Science:

• Materials Science
• Solid State Physics
• Quantum Chemistry

Background:

• Thermoelectric materials convert heat energy into electrical energy.
• Zinc selenide (ZnSe) is a semiconductor with potential thermoelectric applications.
• Understanding impurity effects is crucial for optimizing thermoelectric properties.

Purpose of the Study:

• To investigate the impact of oxygen (O) impurities on the thermoelectric properties of zinc selenide (ZnSe).
• To explore the underlying mechanisms responsible for changes in thermoelectric performance.
• To assess the potential for designing novel thermoelectric materials based on impurity engineering.

Main Methods:

• First-principles calculations to model electronic structure and properties.
• Analytic calculations to complement computational findings.
• Analysis of density of states (DOS) and charge density distribution.

Main Results:

• Oxygen impurities introduce peaks in the density of states (DOS) above the conduction band minimum in ZnSe.
• High electronegativity of oxygen attracts charge density, enhancing DOS peaks.
• Room-temperature Seebeck coefficient and power factor increased by factors of 30 and 180, respectively.
• This enhancement is absent when impurity electronegativity closely matches the host material.

Conclusions:

• Highly electronegative impurities like oxygen can dramatically improve the thermoelectric performance of ZnSe.
• The observed enhancement is linked to impurity-induced modifications in the electronic density of states.
• Designing alloys with significant electronegativity mismatch is a promising strategy for high-performance thermoelectric applications.