Direct Evidence of Permanent Octahedra Distortion in MAPbBr₃ Hybrid Perovskite

In the present Letter, we provide direct experimental evidence of the existence of short-range octahedra distortion in MAPbBr 3 in the tetragonal and cubic phases. Such distortion is analogous to that found in the ordered orthorhombic phase and increases with temperature and symmetry of the unit cell. Such local distortion is most probably correlated with the presence of hydrogen bonding between MA and the PbBr 6 framework, and its evolution with temperature is related to the increase of rotational degrees of freedom of the MA group.