First principles investigation of double perovskites Li2CuAsZ6 (Z = Cl, Br, I) as a suitable alternatives for energy conversion technologies

The present study employs density functional theory to examine the physical properties of halide double perovskites Li2CuAsZ6 (Z = Cl, Br, I). The stability of the phase has been confirmed by analyzing the cubic layout and the values of the octahedral and tolerance factors. The formation energies of all perovskites have been computed to guarantee thermodynamic stability. The detailed description of the electronic characteristics of Li2CuAsZ6 reveals its behavior as a semiconductor. Energy band gaps of 0.55 eV, 0.33 eV, and 0.088 eV for Li2CuAsCl6, Li2CuAsBr6, and Li2CuAsI6, respectively, are determined by our calculations. Additionally, we have investigated the optical properties of these materials with 0-4 eV energy span in detail, which are reported as strong candidates for use in optoelectronic systems. The BoltzTraP code is employed to evaluate the thermoelectric characteristics. The lower lattice thermal conductivity values for Li2CuAsCl6, Li2CuAsBr6, and Li2CuAsI6 suggest less contribution to thermoelectric functionality. Finally, this discussion indicates the suitability of studied perovskites for energy conversion systems; however, experimental confirmation is necessary before these perovskites may be used in thermoelectric and optoelectronic systems.