Design of Multifunctional Quinternary Metal-Halide Perovskite Compounds Based on Cation–Anion Co-Ordering

The intrinsic material instability and toxicity of organic–inorganic hybrid perovskite CH3NH3PbI3 are the main challenges for the large-scale deployment of perovskite solar cells, propelling the search of other promising perovskite absorbers. A halide double perovskite exhibits a highly tunable electronic structure as well as thermodynamic stability, while a mixed-halide perovskite shows the improved phase stability. Combining these advantages, we try to design a type of quinternary perovskite compound based on the cation transmutation analogous to a double perovskite plus anion mixing as in mixed-halide perovskites. This cation–anion co-mixing would lead to thermodynamically stable compounds named dual-double perovskites with ordered double cation and double anion sublattices that minimize the strain and Coulomb energies. We identify, from first-principles high-throughput screening, 12 stable dual-double perovskite compounds, among which Cs2RbYCl4Br2 and Cs2CsYCl4Br2 are potential candidates for ultraviolet photodetectors, while Cs2AgIAuIIIBr4Cl2, Cs2AuIAuIIIBr4Cl2, and Cs2AuIAuIIII4Br2 are possible candidates for solar cell absorbers with a spectroscopic limited maximum efficiency (SLME) of ∼30% in a 0.5 μm-thick film. These AuIII-related compounds also possess highly anisotropic optical properties in bulk form suitable for polarized light detectors. Furthermore, their lowest conduction bands with nominal Au3+ (d8) electron configuration and empty Au-d states are, however, rather dispersive (as well as their highest valence bands) since their actual electron configurations are found to be d9L or d10L2 (where L represents a ligand hole), suggesting good carrier mobility. Our results suggest a new route to design stable perovskite compounds for energy harvesting and optoelectronic applications.