Doping Mn2+ in Single-Crystalline Layered\nPerovskite Microcrystals

While\nsolution-processed doping of Mn ions in 3D lead halide perovskites\nis extensively studied, the chemistry for Mn doping in 2D layered\nperovskites is limited. Following a generic solution-phase colloidal\napproach in the presence of alkylammonium salts, formation of single-crystalline\nmicrocrystals of Mn-doped layered perovskites (L2PbX4, X = Cl, Br, I) is reported. While Mn was present in all\nmicrostructures, only L2PbBr4 led to Mn d–d\nemission with high quantum yield (∼61%). These doped layered\nstructures showed robust stability and even retained the original\nemission in continuous thermocycling or constant heating at 200 °C\nin air for more than 24 h. Moreover, these materials also showed solid-state\nthermal annealing-induced 2D agglomeration leading to a larger structure,\nwhich was reflected from optical microscopic images and the enhanced\nintensity of powder XRD peaks that originated from the layered structure.\nApart from the generic synthesis, these results also provided several\nnew fundamental insights on doping and doped 2D perovskites, which\nwere timely required for the advancement of the materials property\nand understanding the growth mechanism of these materials.