Unraveling exciton–phonon coupling in individual FAPbI3 nanocrystals emitting near-infrared single photons

作者：Ming Fu, Philippe Tamarat, Jean-Baptiste Trebbia, Maryna I. Bodnarchuk, Maksym V. Kovalenko, Jacky Even, Brahim Lounis · 发表于：Nature Communications · 年份：2018 · DOI：10.1038/s41467-018-05876-0 · 被引用次数：171 · 研究领域：Perovskite Materials and Applications、Optical properties and cooling technologies in crystalline materials、Solid State Laser Technologies

Abstract Formamidinium lead iodide (FAPbI3) 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 FAPbI3 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 FAPbI3 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.