First principles investigation of semiconducting and thermoelectric behavior in TiIrBi half-Heusler compound

This study presents a comprehensive first-principles investigation of the half-Heusler (HH) compound TiIrBi, encompassing its structural, electronic, mechanical, optical, and thermoelectric properties. The electronic characteristics were evaluated using density functional theory within both the PBE-GGA and mBJ-GGA exchange-correlation frameworks. The results confirm that TiIrBi is a semiconductor, with mBJ-GGA predicting a direct bandgap of 0.79 eV, significantly larger than the 0.43 eV obtained using PBE-GGA, indicating strong potential for optoelectronic applications. Optical analysis further supports the presence of a direct bandgap and reveals substantial absorption in the visible region. Mechanical stability is confirmed by compliance with the Born stability criteria, while the calculated bulk-to-shear modulus ratio (B/S = 2.02) indicates ductile behavior, favorable for mechanical processing and device integration. Thermoelectric performance analysis reveals promising p-type transport characteristics, with a maximum dimensionless figure of merit of 0.78 at 1200 K. These findings highlight TiIrBi as a promising material for next-generation optoelectronic and thermoelectric applications, supporting the advancement of Ti-based HH compounds in energy and electronics.