Elastic Constants, Optical Phonons, and Molecular Relaxations in the High Temperature Plastic Phase of the CH₃NH₃PbBr₃ Hybrid Perovskite

Antoine Létoublon, Serge Paofai, Benoît Rufflé, Philippe Bourges, Bernard Hehlen, Thierry Michel, Claude Ecolivet, Olivier Durand, Stéphane Cordier, Claudine Katan, Jacky Even

DOI: 10.1021/acs.jpclett.6b01709.
First published online 7 Sep 2016
Paper on ACS website
Paper in open access repository

On the basis of a general symmetry analysis, this paper presents an empirical tight-binding (TB) model for the reference Pm-3m perovskite cubic phase of halide perovskites of general formula ABX₃. The TB electronic band diagram, with and without spin orbit coupling effect of MAPbI₃ has been determined based on state of the art density functional theory results including many body corrections (DFT+GW). It affords access to various properties, including distorted structures, at a significantly reduced computational cost. This is illustrated with the calculation of the band-to-band absorption spectrum, the variation of the band gap under volumetric strain, as well as the Rashba effect for a uniaxial symmetry breaking. Compared to DFT approaches, this empirical model will help to tackle larger issues, such as the electronic band structure of large nanostructures, including many-body effects, or heterostructures relevant to perovskite device modeling suited to the description of atomic-scale features.