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Poster De Conférence Année : 2018

Elastic softness of hybrid lead halide perovskites

Serge Paofai
Stéphane Raymond
Claude Ecolivet
Benoit Rufflé
  • Fonction : Auteur
  • PersonId : 1009987
Claudine Katan
Philippe Bourges

Résumé

Hybrid organic-inorganic perovskites have been intensively studied as promising materials for photovoltaic applications, taking advantage of their high efficiency and low cost processing. Although much recent attention has also been devoted towards unraveling their microscopic optoelectronic properties, the origin of their softness, by comparison to classic semiconductors, is currently still lacking a comprehensive understanding and systematic experimental studies. 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. We report a very small shear C44 elastic constant for all the compounds and a considerable elastic anisotropy. The extremely low bulk modulus and negative C12 in α-FAPbI3 substantiates its very unstable nature and in FAPbBr3, a tendency towards an incipient ferroelastic transition, is interpreted as further evidence of the influence of plasticity in hybrid perovskites. 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.
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Dates et versions

hal-01722941 , version 1 (05-03-2018)

Identifiants

  • HAL Id : hal-01722941 , version 1

Citer

Afonso da Cunha Ferreira, Antoine Létoublon, Serge Paofai, Stéphane Raymond, Claude Ecolivet, et al.. Elastic softness of hybrid lead halide perovskites. International Conference on Perovskite Thin Film Photovoltaics, Photonics and Optoelectronics 2018 (ABXPV&PEROPTO 18), Feb 2018, Rennes, France. 2018. ⟨hal-01722941⟩
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