Elucidating the Mn2+ Dopant Sites in Two-Dimensional Na–In Halide Perovskite

The layered hybrid double perovskites (LDPs) possess excellent stability and environmental friendliness, which makes them remarkable semiconducting materials. Contrary to significant advancements, the nonfluorescent nature at ambient temperature and pressure is still a major hurdle in this intriguing family. Here, we demonstrate doping of the transition metal cation Mn2+ in two-dimensional (2D) (PEA)4NaInCl8 (PEA = phenylethylamine) LDP, by a solution-processed crystallization method. This results in broadband emission at ambient conditions and initial contraction followed by expansion of host lattice on increasing dopant concentration. A higher dopant feed ratio in this wide band gap material leads to the absorption at 2.95 eV due to the 6A1 (6S) → 4A1 (4G) transitions on Mn2+ centers. First-principles calculations based on density functional theory (DFT) confirm that Mn2+ in substitutional sites results in lattice contraction while interstitial site Mn2+ doping leads to lattice expansion. The potential of Mn2+ to improve optical and magnetic properties of host lattice and a deeper understanding of distribution of Mn2+dopant make these LDPs a promising material for emitters for solid-state lighting and magneto-optical applications.