Mixed Anion Semiconductor In₈S_2.82Te_6.18(Te₂)₃

Area of Science:

• Solid-state chemistry
• Materials science
• Crystallography

Background:

• Thermoelectric materials are crucial for waste heat recovery and solid-state cooling.
• Indium chalcogenides are actively researched for their thermoelectric properties.
• Developing new materials with enhanced thermoelectric performance is an ongoing challenge.

Purpose of the Study:

• To synthesize and characterize a novel heteroanionic indium-sulfur-telluride compound.
• To investigate the crystal structure and electronic properties of the new material.
• To evaluate its potential as a p-type thermoelectric material.

Main Methods:

• Single-crystal X-ray diffraction for structural determination.
• Optical measurements to determine the bandgap.
• First-principles density functional theory (DFT) calculations for electronic structure analysis.

Main Results:

• The compound In8S2.82Te6.18(Te2)3 was successfully synthesized and crystallizes in the monoclinic space group C2/c.
• The structure features a 3D framework of corner-connected InQ4 tetrahedra with Te2 dimers.
• An optical bandgap of 1.12 eV and a work function of 5.15 eV were measured.
• DFT calculations revealed multiple overlapping bands near the valence band maximum.

Conclusions:

• The synthesized In8S2.82Te6.18(Te2)3 is a narrow bandgap semiconductor.
• Its electronic band structure, heavy elements, and semiconductor nature suggest potential as a p-type thermoelectric material.
• This discovery opens avenues for further exploration of complex indium chalcogenides for thermoelectric applications.