Doping Mn2+ in Single-Crystalline Layered Perovskite Microcrystals

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