Cation Dynamics and Structural Stabilization in Formamidinium Lead Iodide Perovskites
Artikel i vetenskaplig tidskrift, 2021

The vibrational dynamics of pure and methylammonium-doped formamidinium lead iodide perovskites (FAPbI3) has been investigated by high-resolution neutron spectroscopy. For the first time, we provide an exhaustive and accurate analysis of the cation vibrations and underlying local structure around the organic moiety in these materials using first-principles electronic-structure calculations validated by the neutron data. Inelastic neutron scattering experiments on FAPbI3 provide direct evidence of the formation of a low-temperature orientational glass, unveiling the physicochemical origin of phase metastability in the tetragonal structure. Further analysis of these data provides a suitable starting point to explore and understand the stabilization of the perovskite framework via doping with small amounts of organic cations. In particular, we find that the hydrogen-bonding interactions around the formamidinium cations are strengthened as a result of cage deformation. This synergistic effect across perovskite cages is accompanied by a concomitant weakening of the methylammonium interactions with the surrounding framework.


Kacper Drużbicki

Polish Academy of Sciences

Universidad del Pais Vasco / Euskal Herriko Unibertsitatea

Rasmus Lavén

Chalmers, Kemi och kemiteknik, Energi och material

Jeff Armstrong

STFC Rutherford Appleton Laboratory

Lorenzo Malavasi

Universita degli studi di Pavia

F. Fernandez-Alonso

Universidad del Pais Vasco / Euskal Herriko Unibertsitatea

University College London (UCL)

Donostia International Physics Center

Basque Foundation for Science (Ikerbasque)

Maths Karlsson

Chalmers, Kemi och kemiteknik, Energi och material

Journal of Physical Chemistry Letters

1948-7185 (eISSN)

Vol. 12 14 3503-3508


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