Exploring the potential of double perovskite Rb2SnBr6 for photocatalytic and thermoelectric applications: A DFT study

Addressing the global energy crisis, largely caused by the exhaustion of fossil fuel reserves, requires a transition to clean and sustainable technologies. In this context, lead-free inorganic double perovskites like Rb₂SnBr₆ have emerged as promising alternatives for optoelectronic and photovoltaic applications. This work applies density functional theory (DFT) to explore the structural and essential physical characteristics of Rb₂SnBr₆, with emphasis on its optoelectronic, photocatalytic, thermodynamic, and thermoelectric qualities, underscoring its potential in renewable energy systems. The findings indicate that Rb₂SnBr₆ adopts a cubic crystal structure, with a calculated lattice parameter of a₀ = 10.56 Å. Additionally, its negative formation energy indicates its thermodynamic stability. Analysis of the electronic density of states reveals its p-type semiconducting nature, while the band structure indicates a direct band gap of 2.658 eV. The material exhibits intense optical absorption coefficient exceeding 10⁴ cm⁻¹ in the visible and ultraviolet regions, highlighting its potential for optoelectronic systems. Furthermore, the combination of its electronic and optical features, along with suitable oxidation and reduction potentials for water splitting, suggests that Rb₂SnBr₆ is a promising candidate for photocatalysis. Thermodynamic assessments across varying temperatures and pressures confirm its thermal stability, as well as its notable hardness and resistance to deformation under external stress. Moreover, its potential for thermoelectric applications is supported by its power factor (PF), and other key thermoelectric properties.