Static and Dynamic Disorder in Formamidinium Lead Bromide Single Crystals
Guy Reuveni, Yael Diskin‐Posner, Christian Gehrmann, Shravan Godse, Giannis G. Gkikas, Isaac Buchine, Sigalit Aharon, Roman Korobko, Constantinos C. Stoumpos, David A. Egger, Omer Yaffe
Abstract
We show that formamidinium-based crystals are distinct from methylammonium-based halide perovskite crystals because their inorganic sublattice exhibits intrinsic local static disorder that coexists with a well-defined average crystal structure. Our study combines terahertz-range Raman scattering with single-crystal X-ray diffraction and first-principles calculations to probe the evolution of inorganic sublattice dynamics with temperature in the range of 10-300 K. The temperature evolution of the Raman spectra shows that low-temperature, local static disorder strongly affects the crystal structural dynamics and phase transitions at higher temperatures.