Direct evidence of weakly dispersed and strongly anharmonic optical phonons in hybrid perovskites
Year: 2020
Type: article
Abstract: Hybrid organolead perovskites (HOP) have started to establish themselves in the field of photovoltaics, mainly due to their great optoelectronic properties and steadily improving solar cell efficiency. Study of the lattice dynamics is key in understanding the electron-phonon interactions at play, responsible for such properties. Here, we investigate, via neutron and Raman spectroscopies, the optical phonon spectrum of four different HOP single crystals: MAPbBr3, FAPbBr3, MAPbI3, and α-FAPbI3. Low temperature spectra reveal weakly dispersive optical phonons, at energies as low as 2-5 meV, which seem to be the origin of the limit of the charge carriers mobilities in these materials. The temperature dependence of our neutron spectra shows as well a significant anharmonic behaviour, resulting in optical phonon overdamping at temperatures as low as 80 K, questionning the validity of the quasi-particle picture for the low energy optical modes at room temperature where the solar cells operate.
Source: Communications Physics
Authors: A. C. Ferreira, S. Paofai, A. Létoublon, J. Ollivier, S. Raymond, B. Hehlen, B. Rufflé, S. Cordier, C. Katan, J. Even, P. Bourges
Institutions: Centre National de la Recherche Scientifique, Commissariat à l'Énergie Atomique et aux Énergies Alternatives, Université Paris-Saclay, Institut National des Sciences Appliquées de Rennes, Laboratoire Léon Brillouin, Fonctions Optiques pour les Technologies de l’information, Université de Rennes, Institut des Sciences Chimiques de Rennes, École Nationale Supérieure de Chimie de Rennes, Institut Laue-Langevin, CEA Grenoble, Institut de Recherche Interdisciplinaire de Grenoble, Université de Montpellier, Laboratoire Charles Coulomb
Language: English
Subfield: Electrical and Electronic Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $3,290
OpenAlex ID: W3012252954