Opto‐electronic and thermophysical characteristics of A2TlAgF6 (A = Rb, Cs) for green technology applications

Lead‐free double perovskites are unique materials for transport and optoelectronic applications that use clean resources to generate energy. Using first‐principle computations, this study thoroughly investigates the structural, thermoelectric, and optical attributes of A2TlAgF6 (A = Rb, Cs). Tolerance factor and formation energy estimates are used to verify that these materials exist in the cubic phase. Elastic constants with high melting temperature values are ductile when evaluated for mechanical stability using the Born stability criterion. The optical absorption band is adjusted from 2 to 4 eV via band gaps of 1.88 and 1.99 eV, as indicated by band structures. Analysis of optical properties reveals perfect absorption in the visible spectrum, whole polarization, and low optical loss. Furthermore, thermoelectric properties are assessed at 300, 500, and 700 K in the range of −0.5 to 3 eV for chemical potential (μ). The materials exhibit significant improvements in the Figure of Merit scale due to their elevated electrical conductivity, Seebeck coefficient, and extremely low thermal conductivity values. The dielectric function of A2TlAgF6 (A = Rb, Cs) double perovskites consists of real and imaginary parts. The real part shows the polarization and dispersion of light energy and the imaginary part shows the absorption of light energy. The graphical figure shows the absorption taken in the visible and infrared regions with the highest peaks at 2.9 eV. Contrary to absorption the polarizations or dispersion of light energy is minimal at this point. At resonance frequency, the studied materials are completely polarizations, after a slight shift of frequency the polarization drops, and maximum absorption of light energy takes place.