Computational insights into the role of lattice distorsions in Sb-doped double perovskites

Understanding how lattice distortions influence the electronic structure of metal halide perovskites is essential for designing materials with tunable optical properties. Here, we use density functional theory (DFT) to probe 2D Sb3+-doped (PXA)2NaInCl8 double perovskite, a material that features distinct emission centers. DFT calculations reveal that the Jahn–Teller (JT) effect is the primary mechanism governing electronic-state splitting and emission behavior. Geometry optimizations show significant distortions of the [SbCl₆]³⁻ octahedra, which lift the degeneracy of the key orbitals and produce non-degenerate electronic states. The calculated potential energy surfaces exhibit two distinct radiative minima corresponding to separate emissive centers, while the electronic density of states indicates strong hybridization between Sb 5s/5p and Cl 3p orbitals. These results help rationalize the experimentally observed broadband emission (350–750 nm), providing a microscopic understanding of how structural instabilities can be harnessed to achieve multi-emissive behavior in 2D double perovskites.