Elastic Softness of Hybrid Lead Halide Perovskites

A. C. Ferreira, A. Létoublon, S. Paofai, S. Raymond, C. Ecolivet, B. Rufflé, S. Cordier, C. Katan, Makhsud I. Saidaminov, A. A. Zhumekenov, Osman Bakr, J. Even, P. Bourges

Research output: Contribution to journalArticlepeer-review

55 Scopus citations

Abstract

Much recent attention has been devoted towards unraveling the microscopic optoelectronic properties of hybrid organic-inorganic perovskites. Here we investigate by coherent inelastic neutron scattering spectroscopy and Brillouin light scattering, low frequency acoustic phonons in four different hybrid perovskite single crystals: MAPbBr3, FAPbBr3, MAPbI3, and α-FAPbI3 (MA: methylammonium, FA: formamidinium). We report a complete set of elastic constants characterized by a very soft shear modulus C44. Further, a tendency towards an incipient ferroelastic transition is observed in FAPbBr3. We observe a systematic lower sound group velocity in the technologically important iodide-based compounds compared to the bromide-based ones. The findings suggest that low thermal conductivity and hot phonon bottleneck phenomena are expected to be enhanced by low elastic stiffness, particularly in the case of the ultrasoft α-FAPbI3.
Original languageEnglish (US)
JournalPhysical Review Letters
Volume121
Issue number8
DOIs
StatePublished - Aug 22 2018

Fingerprint

Dive into the research topics of 'Elastic Softness of Hybrid Lead Halide Perovskites'. Together they form a unique fingerprint.

Cite this