Publications

Table of Contents (TOC)

Giant Bandgap Renormalization and Exciton-Phonon Scattering in Perovskite Nanocrystals

Advanced Optical Materials, 2017, 5(17), 1700231

Giant Bandgap Renormalization and Exciton-Phonon Scattering

Abstract

Understanding the interactions between photoexcited charge carriers (electrons and holes) with lattice vibrations (phonons) in quantum confined semiconductor nanocrystals (NCs) is of fundamental interest and a prerequisite for their use in fabricating high-performance optoelectronic devices. Such interactions have a significant impact on their optoelectronic properties including their charge carrier mobility and photoluminescence. Here, we investigate these interactions in cesium lead halide (CsPbX3, where X is Cl, Br, or I) NC perovskites. We show that a wide broadening of the excitonic linewidth in these NCs arises from strong exciton-phonon coupling, which is substantially dominated by longitudinal optical phonons via the Fröhlich interaction. Unlike the behavior of conventional semiconductors, these NCs display a general red-shift of their emission energy peak with reducing temperature. Interestingly, the CsPbCl3 NCs also display an initial blue-shift and undergo a structural phase transition at ~175 K to 200 K. The anomalous red-shift observed is modeled and analyzed using a Bose-Einstein two-oscillator model to interpret the interaction of excitons with acoustic and optical phonons which induce a renormalization of the bandgap. The net renormalization due to zero point motion (T = 0 K) was found to be ~41.6 meV and ~94.9 meV for CsPbBr3 and CsPbI3 NCs respectively.

For citation:
Saran, R.; Heuer-Jungemann, A.; Kanaras, A. G.; Curry, R.
"Giant Bandgap Renormalization and Exciton-Phonon Scattering in Perovskite Nanocrystals"
Adv. Opt. Mater. 2017, 5(17), 1700231. DOI: 10.1002/adom.201700231

PreviousNext