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Coherent Phonons, Localization, and Slow Polaron Formation in Lead-Free Gold Perovskite

Ramesh, Sankaran LU orcid ; Wang, Yonghong ; Chabera, Pavel LU ; Araujo, Rafael ; Aboulsaad, Mustafa ; Edvinsson, Tomas ; Gao, Feng and Pullerits, Tönu LU (2025) In Advanced Optical Materials 13(10).
Abstract

Lead-free metal halide perovskites are emerging as less-toxic alternatives to their lead-based counterparts. However, their applicability in optoelectronic devices is limited, and the charge transport dynamics remain poorly understood. Understanding photo-induced charge and structural dynamics is critical for unlocking the potential of these novel systems. In this work, ultrafast optical and Raman spectroscopy combined with band structure calculations are employed to investigate the coupled electronic and vibrational dynamics in Caesium gold bromide, a promising lead-free perovskite. It is found that the band-edge charge transfer states are strongly coupled to Au─Br stretching phonon modes, leading to frequency modulation of absorption... (More)

Lead-free metal halide perovskites are emerging as less-toxic alternatives to their lead-based counterparts. However, their applicability in optoelectronic devices is limited, and the charge transport dynamics remain poorly understood. Understanding photo-induced charge and structural dynamics is critical for unlocking the potential of these novel systems. In this work, ultrafast optical and Raman spectroscopy combined with band structure calculations are employed to investigate the coupled electronic and vibrational dynamics in Caesium gold bromide, a promising lead-free perovskite. It is found that the band-edge charge transfer states are strongly coupled to Au─Br stretching phonon modes, leading to frequency modulation of absorption by coherent phonons. Early-stage relaxation is characterized by dynamics of delocalized charge transfer excitation and slowly decaying coherent phonons. The electronic and vibrational relaxation reveals a slow formation of a localized polaronic state in the 10–20 ps timescale. Using a displaced harmonic oscillator model, the polaronic binding energy is estimated to be ≈80 meV following lattice relaxation along the phonon modes. Strong exciton-phonon coupling and slow polaron formation via coupling to lattice modes make this material a promising testbed for the control of coherent phonons and localized polaronic states using light.

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author
; ; ; ; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Coherent Phonon, Electron-phonon coupling, Lead-free perovskite, Polaron, Raman
in
Advanced Optical Materials
volume
13
issue
10
article number
2402882
pages
10 pages
publisher
John Wiley & Sons Inc.
external identifiers
  • scopus:85219732388
ISSN
2195-1071
DOI
10.1002/adom.202402882
language
English
LU publication?
yes
additional info
Publisher Copyright: © 2025 The Author(s). Advanced Optical Materials published by Wiley-VCH GmbH.
id
f491f209-e992-4aaf-a0d2-73587a216f93
date added to LUP
2025-03-17 07:53:12
date last changed
2025-04-14 10:03:35
@article{f491f209-e992-4aaf-a0d2-73587a216f93,
  abstract     = {{<p>Lead-free metal halide perovskites are emerging as less-toxic alternatives to their lead-based counterparts. However, their applicability in optoelectronic devices is limited, and the charge transport dynamics remain poorly understood. Understanding photo-induced charge and structural dynamics is critical for unlocking the potential of these novel systems. In this work, ultrafast optical and Raman spectroscopy combined with band structure calculations are employed to investigate the coupled electronic and vibrational dynamics in Caesium gold bromide, a promising lead-free perovskite. It is found that the band-edge charge transfer states are strongly coupled to Au─Br stretching phonon modes, leading to frequency modulation of absorption by coherent phonons. Early-stage relaxation is characterized by dynamics of delocalized charge transfer excitation and slowly decaying coherent phonons. The electronic and vibrational relaxation reveals a slow formation of a localized polaronic state in the 10–20 ps timescale. Using a displaced harmonic oscillator model, the polaronic binding energy is estimated to be ≈80 meV following lattice relaxation along the phonon modes. Strong exciton-phonon coupling and slow polaron formation via coupling to lattice modes make this material a promising testbed for the control of coherent phonons and localized polaronic states using light.</p>}},
  author       = {{Ramesh, Sankaran and Wang, Yonghong and Chabera, Pavel and Araujo, Rafael and Aboulsaad, Mustafa and Edvinsson, Tomas and Gao, Feng and Pullerits, Tönu}},
  issn         = {{2195-1071}},
  keywords     = {{Coherent Phonon; Electron-phonon coupling; Lead-free perovskite; Polaron; Raman}},
  language     = {{eng}},
  month        = {{02}},
  number       = {{10}},
  publisher    = {{John Wiley & Sons Inc.}},
  series       = {{Advanced Optical Materials}},
  title        = {{Coherent Phonons, Localization, and Slow Polaron Formation in Lead-Free Gold Perovskite}},
  url          = {{http://dx.doi.org/10.1002/adom.202402882}},
  doi          = {{10.1002/adom.202402882}},
  volume       = {{13}},
  year         = {{2025}},
}