Interstitial Nature of Mn2+ Doping in 2D Perovskites
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Halide perovskites doped with magnetic impurities (such as the transition metals Mn2+, Co2+, Ni2+) are being explored for a wide range of applications beyond photovoltaics, such as spintronic devices, stable light-emitting diodes, single-photon emitters, and magneto-optical devices. However, despite several recent studies, there is no consensus on whether the doped magnetic ions will predominantly replace the octahedral B-site metal via substitution or reside at interstitial defect sites. Here, by performing correlated nanoscale X-ray microscopy, spatially and 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 show the fate of the transition metal dopants, the local structure, and optical emission when they are doped at dilute concentrations into a wide band gap semiconductor.
author list (cited authors)
Torma, A. J., Li, W., Zhang, H., Tu, Q., Klepov, V. V., Brennan, M. C., ... Mohite, A. D
complete list of authors
Torma, Andrew J||Li, Wenbin||Zhang, Hao||Tu, Qing||Klepov, Vladislav V||Brennan, Michael C||McCleese, Christopher L||Krzyaniak, Matthew D||Wasielewski, Michael R||Katan, Claudine||Even, Jacky||Holt, Martin V||Grusenmeyer, Tod A||Jiang, Jie||Pachter, Ruth||Kanatzidis, Mercouri G||Blancon, Jean-Christophe||Mohite, Aditya D