Super narrow bandgap (<1.2 eV) halide double perovskites: Recent advancements and future perspectives

In recent years, the utilization of perovskite materials attracted significant attention in optoelectronics due to their promising efficiency and cost-effectiveness. Nevertheless, challenges persist in precisely engineering the bandgap of perovskites to below 1.2 eV, a critical requirement for their incorporation in optoelectronic devices spanning interdisciplinary device applications aimed at exploiting the infrared regions. This review suggests halide double perovskites (HDPs) as potential alternatives, offering a comprehensive overview of recent advancements in this field. The study covers both experimental and theoretical approaches. Experimentally, the various compositions, bandgaps, material properties, and diverse preparation techniques for developing super narrow-bandgap (NBG) HDPs are thoroughly discussed. Theoretical perspectives are also explored, examining compositions, bandgap properties, and computational methods. This review explores the defects and associated challenges inherent in super narrow bandgap (NBG) hybrid double perovskites (HDPs), along with their utilization in interdisciplinary applications. It also includes a discussion on strategies to overcome current challenges, suggesting directions for further research, and envisioning potential applications of these materials in optoelectronic devices. Undoubtedly, the in-depth study of super NBG (below 1.2 eV) HDPs is set to have a significant impact on the development of advanced materials for cross-disciplinary device applications.