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Multiband k·p Model for Tetragonal Crystals: Application to Hybrid Halide Perovskite Nanocrystals

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journal contribution
posted on 2020-01-17, 15:41 authored by R. Ben Aich, S. Ben Radhia, K. Boujdaria, M. Chamarro, C. Testelin
We investigate the theoretical band structure of organic–inorganic perovskites APbX3 with tetragonal crystal structure. Using D4h point group symmetry properties, we derive a general 16-band Hamiltonian describing the electronic band diagram in the vicinity of the wave-vector point corresponding to the direct band gap. For bulk crystals, a very good agreement between our predictions and experimental physical parameters, as band gap energies and effective carrier masses, is obtained. Extending this description to three-dimensional confined hybrid halide perovskite, we calculate the size dependence of the excitonic radiative lifetime and fine structure. We describe the exciton fine structure of cube-shaped nanocrystals by an interplay of crystal-field and electron–hole exchange interaction (short- and long-range parts) enhanced by confinement. Using very recent experimental results on FAPbBr3 nanocrystals, we extract the bulk short-range exchange interaction in this material and predict its value in other hybrid compounds. Finally, we also predict the bright–bright and bright–dark splittings as a function of nanocrystal size.

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