Unveiling the Multifunctional Features of Cs ₂ LiMoX ₆ (X = Cl and Br) for Green Energy Applications: A DFT Study

ABSTRACT Double‐perovskite halides are believed to satisfy the requirements for resolving energy scarcity concerns and have the potential to be beneficial materials for the production of renewable energy. Density functional theory modeling was used to analyze the physical properties of Cs 2 LiMoX 6 (X = Cl, Br), with electronic and optical features studied via Tran Blaha‐modified Beche Johnson (TB‐mBJ). Spin‐resolved band structure and density of states confirmed their semiconductor nature. Cs 2 LiMoCl 6 exhibited band gaps of 3.45 eV (spin‐down) and 2.42 eV (spin‐up), while Cs 2 LiMoBr 6 had band gaps of 3.13 eV (spin‐down) and 1.34 eV (spin‐up). The stability of the studied composites was shown by their low ground state energy, elastic constants, and tolerance factor analyses. Both Poisson's and Pugh's ratios indicated that the materials are brittle. The materials absorbed light in the ultraviolet range, specifically from 212 to 327 nm for Cs 2 LiMoCl 6 and from 171 to 385 nm for Cs 2 LiMoBr 6 , indicating that they could be useful for optoelectronic applications. The thermoelectric parameters as a function of temperature were calculated using the Boltztrap code, which has been integrated with the WIEN2K code. At 800 K, the thermoelectric figure of merit ( zT ) values were 0.75 for Cs 2 LiMoCl 6 and 0.86 for Cs 2 LiMoBr 6 , demonstrating their potential for high‐temperature thermoelectric applications.