Investigation of optoelectronic and thermoelectric characteristics of Tl2Os(Cl/Br)6 double perovskites for renewable energy applications

Abstract

Half-metallicity is a promising feature for burgeoning spintronic devices, prompting investigators to explore suitable materials for advancing existing technology. This study delves into the impact of Os d-electrons on the half-metallic ferromagnetic behavior of double perovskites with composition Tl₂Os (Cl/Br)₆, aiming to elucidate their potential for spintronic devices. The structural, electronic, magnetic, and transport responses are comprehensively investigated utilizing the WIEN2k package. The incorporation of Br at Cl site causes the expansion of unit cell from 9.80 to 10.37 Å, reduction of bulk modulus from 50.27 to 41.38 GPa, and formation energy of −9.33 and −7.89 eV for Tl₂OsCl₆ and Tl₂OsBr₆, respectively. The high Curie temperature of 552 and 518 K witness their above-room-temperature viability for device fabrication. Insights into half-metallicity are established from band structures and DOS analysis. The phenomenon of half-metallic ferromagnetism is elucidated through exchange constants and a double exchange mechanism. Furthermore, various thermoelectric performance parameters, including electrical conductivity (σ), thermal conductivity due to electron (κ_e), the seeback coefficient (S), susceptibility (χ), power factor (PF), and figure of merit (ZT) are meticulously calculated. This comprehensive exploration sheds light on the potential of Tl₂Os(Cl/Br)₆ for spintronic applications, underscoring their utilization in emerging technologies.