Browsing by Author "Torma, Andrew J"

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    Nano-imaging to Determine the Interstitial Nature of Mn(II) Doping in 2D Halide Perovskites
    (2022-06-14) Torma, Andrew J; Mohite, Aditya
    Andrew Jonathon Torma By performing correlated nanoscale X-ray microscopy, temporally resolved photoluminescence measurements, and magnetic force microscopy on the inorganic 2D perovskite Cs2PbI2Cl2, we show that doping Mn2+ into the structure results in a lattice expansion. The observed lattice expansion contrasts with the predicted contraction expected to arise from the B-site metal substitution, thus implying that Mn2+ does not replace the Pb2+ sites. Photoluminescence and electron paramagnetic resonance measurements confirm the presence of Mn2+ in the lattice, while correlated nano-XRD and X-ray fluorescence track the local strain and chemical composition. Density functional theory calculations predict that Mn2+ atoms reside at the interstitial sites between two octahedra in the triangle formed by one Cl- and two I- atoms, which results in a locally expanded structure. These measurements shed light on the fate of transition metal dopants, local structure, and optical emission when they are doped at dilute concentrations into a wide band-gap semiconductor.