Mechanical, optical, and thermoelectric properties of α-BaSnS and β-BaSnS.

This study explores the mechanical, optical, and thermoelectric properties of α-BaSnS and β-BaSnS through first-principles calculations. The mechanical analysis reveals that both structures exhibit ductile behaviour. Furthermore, phonon dispersion calculations at 0 K show no imaginary frequencies, confirming their dynamical stability. The electronic structure analysis identifies both compounds as indirect bandgap semiconductors, with a bandgap of 1.63 eV for α-BaSnS and 1.12 eV for β-BaSnS. Optical property analysis indicates that both compounds exhibit high absorption coefficients, reaching up to ∼10 cm in the ultraviolet region and approximately ∼10 cm in the visible spectrum, demonstrating their potential for optoelectronic applications. To explore the thermal transport properties, we calculated the lattice thermal conductivity using particle-like and wave-like transport channels. At 300 K, α-BaSnS exhibits an average of 1.030 W m K and of 0.112 W m K, whereas β-BaSnS exhibits average values of 0.128 W m K for and 0.179 W m K for . This reduction in β-BaSnS is primarily attributed to its pronounced anharmonicity and extremely short phonon lifetimes, which predominantly range from 0.1 to 1 ps. In terms of thermoelectric performance, α-BaSnS achieves a value of 1.05 at 600 K, while β-BaSnS achieves an even higher value of 1.06 under specific doping conditions. These results highlight the potential of the two phases of BaSnS for applications in thermoelectric and optoelectronic technologies.