Tailoring the physical, optoelectronic and transport properties of novel lead-free Sodium perovskites Na2TeX6 (X = Cl, Br, I) using DFT computation for photovoltaic and thermal devices

In this work, we analyzed the system, elastic, electronics, optical, as well as thermoelectric properties of perovskites Na2TeX6 (X = Cl, Br, I) systems using a potential linearization augmented plane Wave method with the help of WIEN2k. code. The tolerance factor, fermi energy, and mechanical characteristics define the stability of perovskites Na2TeX6 (X = Cl, Br, I) systems. The electronic properties were calculated using the generalized gradient plus the modified Becke-Johnson method. The computed values of the compounds Na2TeX6 (X = Cl, Br, I) are 3.15 eV, 2.54 eV, and 1.85 eV, indicating that the analyzed materials have electronic material. We determined the optical characteristics based on the facts and hypotheses of the dielectric function, refractive index, reflection, and absorption coefficients, taking into consideration the usage in photovoltaic and optoelectronic devices. Investigation of their transport characteristics reveals that both materials have been thermodynamically stable. The compounds were predicted in the temperature range of 200-1200 K for electrical properties such as electrical conductance, Seebeck coefficient, thermal conductivity, and power factor. At low temperatures, the compounds had a good Seebeck coefficient, which shows that the hole is the main part of the system and the solids nature is p-type. The perovskites to Na2TeX6 (X = Cl, Br, I) compound's high zT values suggested that they may be employed in thermoelectric devices.