Unraveling exciton-phonon coupling in individual FAPbI<sub>3</sub> nanocrystals emitting near-infrared single photons.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 30127339.
- Also identified by DOI 10.1038/s41467-018-05876-0 and PMC identifier 6102301.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Formamidinium lead iodide (FAPbI<sub>3</sub>) exhibits the narrowest bandgap energy among lead halide perovskites, thus playing a pivotal role for the development of photovoltaics and near-infrared classical or quantum light sources. Here, we unveil the fundamental properties of FAPbI<sub>3</sub> by spectroscopic investigations of nanocrystals of this material at the single-particle level. We show that these nanocrystals deliver near-infrared single photons suitable for quantum communication. Moreover, the low temperature photoluminescence spectra of FAPbI<sub>3</sub> nanocrystals reveal the optical phonon modes responsible for the emission line broadening with temperature and a vanishing exciton-acoustic phonon interaction in these soft materials. The photoluminescence decays are governed by thermal mixing between fine structure states, with a two-optical phonon Raman scattering process. These results point to a strong Frölich interaction and to a phonon glass character that weakens the interactions of charge carriers with acoustic phonons and thus impacts their relaxation and mobility in these perovskites.