| Literature DB >> 30192590 |
A C Ferreira1,2, A Létoublon2, S Paofai3, S Raymond4, C Ecolivet5, B Rufflé6, S Cordier3, C Katan3, M I Saidaminov7, A A Zhumekenov7, O M Bakr7, J Even2, P Bourges1.
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: MAPbBr_{3}, FAPbBr_{3}, MAPbI_{3}, and α-FAPbI_{3} (MA: methylammonium, FA: formamidinium). We report a complete set of elastic constants characterized by a very soft shear modulus C_{44}. Further, a tendency towards an incipient ferroelastic transition is observed in FAPbBr_{3}. 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-FAPbI_{3}.Entities:
Year: 2018 PMID： 30192590 DOI： 10.1103/PhysRevLett.121.085502
Source DB: PubMed Journal: Phys Rev Lett ISSN： 0031-9007 Impact factor: 9.161