Atomic-Level Description of Thermal Fluctuations in Inorganic Lead Halide Perovskites
Journal article, 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.
Author
Oliviero Cannelli
Swiss Federal Institute of Technology in Lausanne (EPFL)
Julia Wiktor
Chalmers, Physics, Condensed Matter and Materials Theory
Nicola Colonna
Swiss Federal Institute of Technology in Lausanne (EPFL)
Paul Scherrer Institut
Ludmila Leroy
Universidade Federal de Minas Gerais
Swiss Federal Institute of Technology in Lausanne (EPFL)
Michele Puppin
Swiss Federal Institute of Technology in Lausanne (EPFL)
Camila Bacellar
Paul Scherrer Institut
Ilia Sadykov
Paul Scherrer Institut
Franziska Krieg
Swiss Federal Institute of Technology in Zürich (ETH)
Swiss Federal Laboratories for Materials Science and Technology (Empa)
Grigory Smolentsev
Paul Scherrer Institut
Maksym V. Kovalenko
Swiss Federal Institute of Technology in Zürich (ETH)
Swiss Federal Laboratories for Materials Science and Technology (Empa)
Alfredo Pasquarello
Swiss Federal Institute of Technology in Lausanne (EPFL)
Majed Chergui
Swiss Federal Institute of Technology in Lausanne (EPFL)
Giulia F. Mancini
Universita degli studi di Pavia
Journal of Physical Chemistry Letters
1948-7185 (eISSN)
Vol. 13 15 3382-3391Subject Categories
Inorganic Chemistry
Other Physics Topics
Condensed Matter Physics
DOI
10.1021/acs.jpclett.2c00281
PubMed
35404613