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Giant bandgap renormalization and exciton-phonon scattering in perovskite nanocrystals

Giant bandgap renormalization and exciton-phonon scattering in perovskite nanocrystals
Giant bandgap renormalization and exciton-phonon scattering in perovskite nanocrystals
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 at 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.

Saran, Rinku
f3d09fa8-9ba8-478e-8f17-03748b864c56
Kanaras, Antonios
667ecfdc-7647-4bd8-be03-a47bf32504c7
Heuer-Jungemann, Amelie
48f01a95-9ba4-4248-bd24-0e20d601d2cc
Curry, Richard J.
409b626f-f0b9-4b5e-a12c-6f8b87d20ee0
Saran, Rinku
f3d09fa8-9ba8-478e-8f17-03748b864c56
Kanaras, Antonios
667ecfdc-7647-4bd8-be03-a47bf32504c7
Heuer-Jungemann, Amelie
48f01a95-9ba4-4248-bd24-0e20d601d2cc
Curry, Richard J.
409b626f-f0b9-4b5e-a12c-6f8b87d20ee0

Saran, Rinku, Kanaras, Antonios, Heuer-Jungemann, Amelie and Curry, Richard J. (2017) Giant bandgap renormalization and exciton-phonon scattering in perovskite nanocrystals. Advanced Optical Materials. (In Press)

Record type: Article

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 at 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.

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Giant_Bandgap_Renormalization_and_Exciton - Accepted Manuscript
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Accepted/In Press date: 5 May 2017
Organisations: Quantum, Light & Matter Group

Identifiers

Local EPrints ID: 411616
URI: https://eprints.soton.ac.uk/id/eprint/411616
PURE UUID: 88c20e56-a7a0-4ff9-a760-75cb5148781a
ORCID for Antonios Kanaras: ORCID iD orcid.org/0000-0002-9847-6706

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Date deposited: 21 Jun 2017 16:31
Last modified: 14 Mar 2019 05:49

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Contributors

Author: Rinku Saran
Author: Amelie Heuer-Jungemann
Author: Richard J. Curry

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