Comprehensive exploration of halide double perovskites Cs₂BʹGeCl₆ (Bʹ: Zn, Cd) for affordable energy technologies: a high-throughput investigation

In this study, we have investigated a range of structural, elastic, electronic, optical, and thermoelectric properties of halide double perovskites Cs₂BʹGeCl₆ (Bʹ: Zn, Cd). Our analysis was conducted using the full potential linearized augmented plane wave (FP-LAPW) method with the generalized gradient approximation (GGA) and the modified Becke–Johnson (mBJ) potential. Structural parameters were determined through optimization and analytical schemes, allowing us to precisely define the crystal structure. Elastic properties, including elastic constants, shear modulus, Young’s modulus, anisotropy factor, and Poisson’s ratio, were calculated to assess the materials’ mechanical characteristics. The electronic properties of these double perovskites reveal their semiconductor nature, characterized by an indirect energy band gap (Xv-Lc). Optical properties, including as the dielectric function, absorption coefficient, refractive index, extinction coefficient, reflectivity, electron energy loss, and optical conductivity, were computed across a photon energy range up to 13.0 eV to elucidate the optical response of the materials. Additionally, we predicted the thermoelectric properties of Cs₂BʹGeCl₆ (Bʹ: Zn, Cd) by calculating key thermoelectric coefficients, including the Seebeck coefficient and power factor. Our findings suggest the potential suitability of Cs₂BʹGeCl₆ (Bʹ: Zn, Cd) double perovskites for applications in photovoltaic and thermoelectric devices.