Investigating the Physical Properties of Halide Double Perovskites Cs ₂ AuAsX ₆ (X = Cl, Br, I) for Solar Energy Conversion and Recycling of Waste Heat Applications

ABSTRACT Structural, electronic, optical, mechanical, and thermoelectric qualities for Cs 2 AuAsX 6 (X = Cl, Br, I) have been studied by first‐principles calculations. Mechanical, thermal, and structural stabilities are guaranteed from Born–Huang conditions, formation energy, and tolerance factor. Key elastic qualities like elastic constants, moduli, ductility, and Debye temperature have been estimated and it was concluded that these compounds (Cs 2 AuAsCl 6 , Cs 2 AuAsBr 6 , and Cs 2 AuAsI 6 ) are ductile and flexible to act as flexible solar materials. Related band gaps from calculated findings are observed to be 1.1, 0.7, and 0.2 eV accordingly, confirming their semiconducting nature by indirect band gaps and display strong absorption in the visible region. A density of states analysis provides evidence regarding electronic states taken for transitions. Optical property reveals bulk and infrared strong absorptions good for photovoltaic purposes. Low thermal conductivity and high power factors result in high figure‐of‐merit (ZT) values for materials with good waste heat conversion efficiency. Overall, these materials have bright prospects for both photovoltaic and thermoelectric uses.