Probing Optoelectronic Properties of Stable Vacancy‐Ordered Double Perovskites: Insights from Many‐Body Perturbation Theory

vacancy‐ordered double perovskites (VODPs) have captured substantial research interest in the scientific community as they offer environmentally friendly and stable alternatives to lead halide perovskites. In this study, the investigation is focused on (B = Ti, Se, Ru, Pd) VODPs as promising optoelectronic materials employing state‐of‐the‐art first‐principles‐based methodologies, specifically density functional theory combined with density functional perturbation theory (DFPT) and many‐body perturbation theory (within the framework of GW and BSE). These calculations reveal that all these materials possess a cubic lattice structure and are both dynamically and mechanically stable. Interestingly, they all exhibit indirect bandgaps, except displays a metallic character. The bandgap values for these compounds fall within the range of 3.63 to 5.14 eV. Additionally, the results of the BSE indicate that they exhibit exceptional absorption capabilities across the near‐UV to mid‐UV light region. Furthermore, studies on transport and excitonic properties suggest that they exhibit lower effective electron masses compared to holes, with exciton binding energies spanning between 0.16 and 0.98 eV. A significant observation is the prevalent hole‐phonon coupling compared to electron‐phonon coupling in these compounds. Overall, this study provides valuable insights to guide the design of vacancy‐ordered double perovskites as promising lead‐free candidates for future optoelectronic applications.