Atomic-Level Description of Thermal Fluctuations in Inorganic Lead Halide Perovskites
Artikel i vetenskaplig tidskrift, 2022
A comprehensive microscopic description of thermally induced distortions in lead halide perovskites is crucial for their realistic applications, yet still unclear. Here, we quantify the effects of thermal activation in CsPbBr3 nanocrystals across length scales with atomic-level precision, and we provide a framework for the description of phase transitions therein, beyond the simplistic picture of unit-cell symmetry increase upon heating. The temperature increase significantly enhances the short-range structural distortions of the lead halide framework as a consequence of the phonon anharmonicity, which causes the excess free energy surface to change as a function of temperature. As a result, phase transitions can be rationalized via the soft-mode model, which also describes displacive thermal phase transitions in oxide perovskites. Our findings allow to reconcile temperature-dependent modifications of physical properties, such as changes in the optical band gap, that are incompatible with the perovskite time- and space-average structures.
Författare
Oliviero Cannelli
Ecole Polytechnique Federale de Lausanne (EPFL)
Julia Wiktor
Chalmers, Fysik, Kondenserad materie- och materialteori
Nicola Colonna
Ecole Polytechnique Federale de Lausanne (EPFL)
Paul Scherrer Institut
Ludmila Leroy
Universidade Federal de Minas Gerais
Ecole Polytechnique Federale de Lausanne (EPFL)
Michele Puppin
Ecole Polytechnique Federale de Lausanne (EPFL)
Camila Bacellar
Paul Scherrer Institut
Ilia Sadykov
Paul Scherrer Institut
Franziska Krieg
Eidgenössische Technische Hochschule Zürich (ETH)
Eidgenössische Materialprüfungs- und Forschungsanstalt (Empa)
Grigory Smolentsev
Paul Scherrer Institut
Maksym V. Kovalenko
Eidgenössische Technische Hochschule Zürich (ETH)
Eidgenössische Materialprüfungs- und Forschungsanstalt (Empa)
Alfredo Pasquarello
Ecole Polytechnique Federale de Lausanne (EPFL)
Majed Chergui
Ecole Polytechnique Federale de Lausanne (EPFL)
Giulia F. Mancini
Universita degli studi di Pavia
Journal of Physical Chemistry Letters
1948-7185 (eISSN)
Vol. 13 15 3382-3391Ämneskategorier
Oorganisk kemi
Annan fysik
Den kondenserade materiens fysik
DOI
10.1021/acs.jpclett.2c00281
PubMed
35404613