Structural, optoelectronics and thermoelectric properties of K2AuSbX6 (X = Cl, Br, I) halide double perovskites; DFT study

The global push for renewable energy has driven the search for efficient, environmentally friendly materials, particularly in the realm of optoelectronics. Traditional perovskites, despite their exceptional properties, are often lead-based, posing significant environmental and health risks. To address these concerns, this study investigates K₂AuSbX₆ (X = Cl, Br, I) halide double perovskites as promising lead-free alternatives using density functional theory (DFT) calculations. Our findings reveal that K₂AuSbX₆ compounds are structurally stable across all halide substitutions, with lattice parameters increasing from Cl to I. The band gap analysis shows that K₂AuSbCl₆, with its wider band gap, is suitable for UV applications, while K₂AuSbI₆, with its narrower band gap, is ideal for visible and near-infrared regions. Additionally, the optical properties, such as absorption coefficients and refractive indices, exhibit tunable behavior, enhancing the versatility of these materials for various optoelectronic applications. In terms of thermoelectric properties, K₂AuSbBr₆ emerges as the most promising candidate due to its higher Seebeck coefficient and power factor, suggesting its potential for efficient thermoelectric devices. Overall, this study establishes K₂AuSbX₆ perovskites as viable, environmentally benign materials with significant potential in both optoelectronic and thermoelectric applications, warranting further experimental exploration.