Designing high-performance thermoelectrics through chalcogen engineering in InSe-based layered materials.

Area of Science:

• Materials Science
• Condensed Matter Physics
• Solid State Chemistry

Background:

• Van der Waals layered materials like InSe exhibit unique electronic and thermal properties.
• Breaking local inversion symmetry is crucial for exploring novel material functionalities.
• Chalcogen substitution offers a pathway to tune material characteristics.

Purpose of the Study:

• Investigate the impact of chalcogen substitution (S, Se, Te) on InSe-based materials.
• Analyze the resulting structural, mechanical, electronic, and thermoelectric property changes.
• Identify strategies for optimizing thermoelectric performance in these layered systems.

Main Methods:

• Computational investigation of InXY (X,Y = S, Se, Te) layered materials.
• Analysis of structural distortions, lattice dynamics, and electronic band structures.
• Evaluation of thermoelectric figure of merit (ZT) through phonon scattering and carrier transport mechanisms.

Main Results:

• Chalcogen substitution induces lattice distortions, affecting symmetry and bonding.
• Sulfur substitution drives a direct-to-indirect band-gap transition.
• Te-substituted systems exhibit enhanced charge delocalization and carrier transport.
• Phonon scattering is enhanced by Te-induced softening and S-induced stiffening.
• InSe0.5Te0.5 achieves a high n-type ZT of 3.08; InS0.5Te0.5 shows a p-type ZT of 1.17.

Conclusions:

• Targeted chalcogen substitution effectively tunes electronic and phononic transport in InSe.
• Robust structural stability is maintained alongside enhanced thermoelectric performance.
• Te substitution is key for high n-type and p-type thermoelectric figures of merit.