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 3382-3391

Subject Categories

Inorganic Chemistry

Other Physics Topics

Condensed Matter Physics

DOI

10.1021/acs.jpclett.2c00281

PubMed

35404613

More information

Latest update

5/5/2022 1