We combine low frequency Raman scattering measurements with first-principles molecular dynamics (MD) to study the nature of dynamic disorder in hybrid lead-halide perovskite crystals. We conduct a comparative study between a hybrid (CH3NH3PbBr3) and an all-inorganic lead-halide perovskite (CsPbBr3). Both are of the general ABX3 perovskite formula, and have a similar band gap and structural phase sequence, orthorhombic at low temperature, changing first to tetragonal and then to cubic symmetry as temperature increases. In the high temperature phases, we find that both compounds show a pronounced Raman quasi-elastic central peak, indicating that both are dynamically disordered.
Omer Yaffe, Yinsheng Guo, Trevor Hull, Costas Stoumpos, Liang Z. Tan, David A. Egger, Fan Zheng, Guilherme Szpak, Octavi E. Semonin, Alexander N. Beecher, Tony F. Heinz, Leeor Kronik, Andrew M. Rappe, Mercouri G. Kanatzidis, Jonathan S. Owen, Marcos A. Pimenta, and Louis E. Brus, "The nature of dynamic disorder in lead halide perovskite crystals
(Conference Presentation)," Proc. SPIE 9923, Physical Chemistry of Interfaces and Nanomaterials XV, 99231B (Presented at SPIE Nanoscience + Engineering: August 31, 2016; Published: 11 November 2016); https://doi.org/10.1117/12.2236330.5161498054001.
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