DFT insights on the chloride double perovskites X2AuBiCl6 (X = K, Rb, and Cs) with semiconductor nature for PV and optoelectronic applications

In this work, we investigate the comprehensive analysis's structural, elastic, mechanical, thermodynamic, electronic, optical, and thermoelectric properties of chloride double perovskites X2AuBiCl6 with (X = K, Rb, and Cs) using DFT implemented by the Wien2k. The optimized results reveal that all compounds crystallize in cubic (Fm-3m) structure with FM phase. The calculated tolerance factors and formation energy show all X2AuBiCl6 are stable. Also, the computed elastic constants and relatives reveal that X2AuBiCl6 compounds are mechanically and thermodynamically stable and have ductile and anisotropic natures. Also, they show remarkable thermodynamic parameters like Debye temperature, sound velocity, and melting point temperature. The electronic calculations show that compounds are in semiconductor nature with indirect 0.404, 0.410, and 0.422 eV bandgaps. The optical properties were evaluated in the range 0-35 eV, confirming distinct absorption of X2AuBiCl6 within the visible region, highlighting their considerable promise for optoelectronic device innovations. They show unique thermoelectric characteristics like Seebeck coefficient, thermal and electrical conductivity, power factor, figure of merit, and heat capacity at different temperatures. The examined halide perovskites exhibit superior absorption and figure of merit compared to their analogues; thus, they lay the foundation for significant improvements in PVs, solar cells, and other energy conversion applications.