Abstract
We determine the impact of anharmonic thermal vibrations on the fundamental band gap of CsPbBr3, a prototypical model system for the broader class of halide perovskite semiconductors. Through first-principles molecular dynamics and stochastic calculations, we find that anharmonic fluctuations are a key effect in the electronic structure of these materials. We present experimental and theoretical evidence that important characteristics, such as a mildly changing band-gap value across a temperature range that includes phase transitions cannot be explained by harmonic phonons thermally perturbing an average crystal structure and symmetry. Instead, the thermal characteristics of the electronic structure are microscopically connected to anharmonic vibrational contributions to the band gap that reach a fairly large magnitude of 450 meV at 425 K.
| Original language | English |
|---|---|
| Article number | L092401 |
| Number of pages | 7 |
| Journal | Physical Review Materials |
| Volume | 7 |
| Issue number | 9 |
| DOIs | |
| Publication status | Published - Sept 2023 |
Funding
Funding Information: We thank A. Chernikov (TU Dresden) for fruitful discussions. Funding provided by the Alexander von Humboldt Foundation in the framework of the Sofja Kovalevskaja Award, endowed by the German Federal Ministry of Education and Research, by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) via SPP2196 Priority Program (Project ID No. 424709454) and via Germany's Excellence Strategy-EXC 2089/1-390776260, and by the Technical University of Munich-Institute for Advanced Study, funded by the German Excellence Initiative and the European Union Seventh Framework Programme under Grant Agreement No. 291763, are gratefully acknowledged. We further acknowledge the Gauss Centre for Supercomputing e.V. for funding this project by providing computing time through the John von Neumann Institute for Computing on the GCS Supercomputer JUWELS at Jülich Supercomputing Centre. O.Y. acknowledges funding from European Research Council (850041-ANHARMONIC). Publisher Copyright: © 2023 American Physical Society.
All Science Journal Classification (ASJC) codes
- General Materials Science
- Physics and Astronomy (miscellaneous)