Colloidal Mn-Doped Cesium Lead Halide Perovskite Nanoplatelets

Abstract

Strong\nquantum confinement in Mn-doped semiconductor nanocrystals\nenhances dopant–carrier exchange interactions. Here, we report\nthe synthesis and optical properties of strongly quantum confined,\nquasi two-dimensional, Mn-doped CsPbCl₃ nanoplatelets.\nA room-temperature synthesis was employed to prepare the platelets\nwith thickness 2.2 nm (4 monolayers), which is significantly smaller\nthan the Bohr excitonic diameter of CsPbCl₃ (5 nm). Efficient\ntransfer of excitonic energy from the host to the Mn²⁺ dopant\nions leads to a spin-forbidden ⁴T₁–⁶A₁ Mn d-electron emission with the highest quantum\nyield of ∼20% and exhibits a long lifetime of 1.6 ms. Subsequent\nanion exchange reactions at room temperature lead to the formation\nof Mn-doped CsPbBr₃ nanoplatelets, with weak Mn emission.\nThese newly developed Mn-doped cesium lead halide nanoplatelets are\nsuitable candidates for exploring the effects of quantum confinement\non dopant–carrier exchange interaction and exhibiting interesting\nmagneto-optic properties.