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Exciton Binding Energy and the Nature of Emissive States in Organometal Halide Perovskites.

Zheng, Kaibo LU ; Zhu, Qiushi LU ; Qenawy, Mohamed LU ; Messing, Maria LU ; Zhang, Wei LU ; Generalov, Alexander LU ; Niu, Yuran LU ; Ribaud, Lynn; Canton, Sophie E and Pullerits, Tönu LU (2015) In The Journal of Physical Chemistry Letters 6(15). p.2969-2975
Abstract
Characteristics of nanoscale materials are often different from the corresponding bulk properties providing new, sometimes unexpected, opportunities for applications. Here we investigate the properties of 8 nm colloidal nanoparticles of MAPbBr3 perovskites and contrast them to the ones of large microcrystallites representing a bulk. X-ray spectroscopies provide an exciton binding energy of 0.32 ± 0.10 eV in the nanoparticles. This is 5 times higher than the value of bulk crystals (0.084 ± 0.010 eV), and readily explains the high fluorescence quantum yield in nanoparticles. In the bulk, at high excitation concentrations, the fluorescence intensity has quadratic behavior following the Saha-Langmuir model due to the nongeminate recombination... (More)
Characteristics of nanoscale materials are often different from the corresponding bulk properties providing new, sometimes unexpected, opportunities for applications. Here we investigate the properties of 8 nm colloidal nanoparticles of MAPbBr3 perovskites and contrast them to the ones of large microcrystallites representing a bulk. X-ray spectroscopies provide an exciton binding energy of 0.32 ± 0.10 eV in the nanoparticles. This is 5 times higher than the value of bulk crystals (0.084 ± 0.010 eV), and readily explains the high fluorescence quantum yield in nanoparticles. In the bulk, at high excitation concentrations, the fluorescence intensity has quadratic behavior following the Saha-Langmuir model due to the nongeminate recombination of charges forming the emissive exciton states. In the nanoparticles, a linear dependence is observed since the excitation concentration per particle is significantly less than one. Even the bulk shows linear emission intensity dependence at lower excitation concentrations. In this case, the average excitation spacing becomes larger than the carrier diffusion length suppressing the nongeminate recombination. From these considerations we obtain the charge carrier diffusion length in MAPbBr3 of 100 nm. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
The Journal of Physical Chemistry Letters
volume
6
issue
15
pages
2969 - 2975
publisher
The American Chemical Society
external identifiers
  • pmid:26267190
  • wos:000359333100022
  • scopus:84938693001
ISSN
1948-7185
DOI
10.1021/acs.jpclett.5b01252
language
English
LU publication?
yes
id
67345358-1e49-4f41-a97b-c6f6920f9d71 (old id 7844132)
date added to LUP
2015-09-10 20:10:49
date last changed
2017-10-29 03:49:26
@article{67345358-1e49-4f41-a97b-c6f6920f9d71,
  abstract     = {Characteristics of nanoscale materials are often different from the corresponding bulk properties providing new, sometimes unexpected, opportunities for applications. Here we investigate the properties of 8 nm colloidal nanoparticles of MAPbBr3 perovskites and contrast them to the ones of large microcrystallites representing a bulk. X-ray spectroscopies provide an exciton binding energy of 0.32 ± 0.10 eV in the nanoparticles. This is 5 times higher than the value of bulk crystals (0.084 ± 0.010 eV), and readily explains the high fluorescence quantum yield in nanoparticles. In the bulk, at high excitation concentrations, the fluorescence intensity has quadratic behavior following the Saha-Langmuir model due to the nongeminate recombination of charges forming the emissive exciton states. In the nanoparticles, a linear dependence is observed since the excitation concentration per particle is significantly less than one. Even the bulk shows linear emission intensity dependence at lower excitation concentrations. In this case, the average excitation spacing becomes larger than the carrier diffusion length suppressing the nongeminate recombination. From these considerations we obtain the charge carrier diffusion length in MAPbBr3 of 100 nm.},
  author       = {Zheng, Kaibo and Zhu, Qiushi and Qenawy, Mohamed and Messing, Maria and Zhang, Wei and Generalov, Alexander and Niu, Yuran and Ribaud, Lynn and Canton, Sophie E and Pullerits, Tönu},
  issn         = {1948-7185},
  language     = {eng},
  number       = {15},
  pages        = {2969--2975},
  publisher    = {The American Chemical Society},
  series       = {The Journal of Physical Chemistry Letters},
  title        = {Exciton Binding Energy and the Nature of Emissive States in Organometal Halide Perovskites.},
  url          = {http://dx.doi.org/10.1021/acs.jpclett.5b01252},
  volume       = {6},
  year         = {2015},
}